July 2018

Pasquale LR, Kang JH, Fan BJ, Levkovitch-Verbin H, Wiggs JL. LOXL1 Polymorphisms: Genetic Biomarkers that Presage Environmental Determinants of Exfoliation Syndrome. J Glaucoma 2018;27 Suppl 1:S20-S23.Abstract
An agnostic high throughput search of the genome revealed a robust association between LOXL1 genetic polymorphisms and exfoliation syndrome (XFS), a discovery that likely would not have been possible with candidate or family-based gene search strategies. While questions remain regarding how LOXL1 gene variants contribute to XFS pathogenesis, it is clear that the frequencies of disease-related alleles do not track with the varying disease burden throughout the world, prompting a search for environmental risk factors. A geo-medicine approach revealed that disease load seemed to increase as a function of the distance from the equator. The exact reason for this extraequatorial disease distribution pattern remains unclear, but a greater amount of time spent outdoors is a robust risk factor for XFS, suggesting climatic factors such as ocular solar exposure and colder ambient temperature may be involved in disease pathogenesis. Prospective studies have also implicated higher coffee consumption and lower dietary folate intake in association with incident XFS. The discovery of environmental risk factors for XFS suggests that preventive measures may help to reduce ocular morbidity from XFS.
He M, Lippestad M, Li D, Hodges RR, Utheim TP, Dartt DA. Activation of the EGF Receptor by Histamine Receptor Subtypes Stimulates Mucin Secretion in Conjunctival Goblet Cells. Invest Ophthalmol Vis Sci 2018;59(8):3543-3553.Abstract
Purpose: The purpose of this study was to determine if histamine receptors interact with the epidermal growth factor receptor (EGFR) in cultured rat conjunctival goblet cells. Methods: Goblet cells from rat conjunctiva were grown in organ culture. First-passage goblet cells were used in all experiments. Phosphorylated (active) and total EGFR, AKT, and extracellular signal-regulated kinase (ERK)1/2 were measured by Western blot analysis. Cells were preincubated with the EGFR antagonist AG1478 for 30 minutes or small interfering RNA specific to the EGFR for 3 days prior to stimulation with histamine or agonists specific for histamine receptor subtypes for 2 hours. Goblet cell secretion was measured using an enzyme-linked lectin assay. Goblet cells were incubated for 1 hour with the calcium indicator molecule fura-2/AM, and intracellular [Ca2+] ([Ca2+]i) was determined. Data were collected in real time and presented as the actual [Ca2+]i with time and as the change in peak [Ca2+]i. Results: Histamine increased the phosphorylation of the EGFR. Mucin secretion and increase in [Ca2+]i stimulated by histamine, and agonists specific for each histamine receptor subtype were blocked by inhibition of the EGFR. Increase in [Ca2+]i stimulated by histamine and specific agonists for each histamine receptor was also inhibited by TAPI-1, a matrix metalloproteinase (MMP) inhibitor. The histamine-stimulated increase in activation of AKT, but not ERK1/2, was blocked by AG1478. Conclusions: In conjunctival goblet cells, histamine, using all four receptor subtypes, transactivates the EGFR via an MMP. This in turn phosphorylates AKT to increase [Ca2+]i and stimulate mucin secretion.
Utheim OA, Lyberg T, Eidet JR, Raeder S, Sehic A, Roald B, Messelt E, de la Paz MF, Dartt DA, Utheim TP. Effect of Transportation on Cultured Limbal Epithelial Sheets for Worldwide Treatment of Limbal Stem Cell Deficiency. Sci Rep 2018;8(1):10502.Abstract
Limbal stem cell deficiency can be treated with transplantation of cultured human limbal epithelial cells (LEC). It can be advantageous to produce LEC in centralized labs and thereafter ship them to eye clinics. The present study used transport simulations of LEC to determine if vigorous shaking during transport altered the viability, morphology and phenotype during a 4 day-long storage of LEC with a previously described serum-free storage method. Inserts with LEC cultured on amniotic membranes were sutured to caps inside air-tight containers with generous amounts of 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES)-buffered minimal essential medium (MEM). The containers were distributed among the following testing conditions: 6 hours with full containers, 36 hours with full containers, 36 hours with container three quarters full of medium, and 36 hours with container full of medium containing a shear-protecting agent (Pluronic-F68). Compared to stored, but non-transported controls, no statistically significant changes in viability and immunohistochemical staining were observed. The epithelial sheets remained intact. However, an air-liquid interface in the containers reduced the number of desmosomes and hemi-desmosomes compared to the controls. In conclusion, cultured LEC sheets appear to endure vigorous shaking for at least 36 hours if the container is full.
Jorge AM, Melles RB, Zhang Y, Lu N, Rai SK, Young LH, Costenbader KH, Ramsey-Goldman R, Lim SS, Esdaile JM, Clarke AE, Urowitz MB, Askanase A, Aranow C, Petri M, Choi H. Hydroxychloroquine prescription trends and predictors for excess dosing per recent ophthalmology guidelines. Arthritis Res Ther 2018;20(1):133.Abstract
BACKGROUND: Hydroxychloroquine (HCQ) retinopathy may be more common than previously recognized; recent ophthalmology guidelines have revised recommendations from ideal body weight (IBW)-based dosing to actual body weight (ABW)-based dosing. However, contemporary HCQ prescribing trends in the UK remain unknown. METHODS: We examined a UK general population database to investigate HCQ dosing between 2007 and 2016. We studied trends of excess HCQ dosing per ophthalmology guidelines (defined by exceeding 6.5 mg/kg of IBW and 5.0 mg/kg of ABW) and determined their independent predictors using multivariable logistic regression analyses. RESULTS: Among 20,933 new HCQ users (78% female), the proportions of initial HCQ excess dosing declined from 40% to 36% using IBW and 38% to 30% using ABW, between 2007 and 2016. Among these, 47% of women were excess-dosed (multivariable OR 12.52; 95% CI 10.99-14.26) using IBW and 38% (multivariable OR 1.98; 95% CI,1.81-2.15) using ABW. Applying IBW, 37% of normal and 44% of obese patients were excess-dosed; however, applying ABW, 53% of normal and 10% of obese patients were excess-dosed (multivariable ORs = 1.61 and 0.1 (reference = normal); both p < 0.01). Long-term HCQ users showed similar excess dosing. CONCLUSION: A substantial proportion of HCQ users in the UK, particularly women, may have excess HCQ dosing per the previous or recent weight-based guidelines despite a modest decline in recent years. Over half of normal-BMI individuals were excess-dosed per the latest guidelines. This implies the potential need to reduce dosing for many patients but also calls for further research to establish unifying evidence-based safe and effective dosing strategies.
Moos WH, Faller DV, Glavas IP, Harpp DN, Irwin MH, Kanara I, Pinkert CA, Powers WR, Steliou K, Vavvas DG, Kodukula K. A New Approach to Treating Neurodegenerative Otologic Disorders. Biores Open Access 2018;7(1):107-115.Abstract
Hearing loss, the most common neurological disorder and the fourth leading cause of years lived with disability, can have profound effects on quality of life. The impact of this "invisible disability," with significant consequences, economic and personal, is most substantial in low- and middle-income countries, where >80% of affected people live. Given the importance of hearing for communication, enjoyment, and safety, with up to 500 million affected globally at a cost of nearly $800 billion/year, research on new approaches toward prevention and treatment is attracting increased attention. The consequences of noise pollution are largely preventable, but irreversible hearing loss can result from aging, disease, or drug side effects. Once damage occurs, treatment relies on hearing aids and cochlear implants. Preventing, delaying, or reducing some degree of hearing loss may be possible by avoiding excessive noise and addressing major contributory factors such as cardiovascular risk. However, given the magnitude of the problem, these interventions alone are unlikely to be sufficient. Recent advances in understanding principal mechanisms that govern hearing function, together with new drug discovery paradigms designed to identify efficacious therapies, bode well for pharmaceutical intervention. This review surveys various causes of loss of auditory function and discusses potential neurological underpinnings, including mitochondrial dysfunction. Mitochondria mitigate cell protection, survival, and function and may succumb to cumulative degradation of energy production and performance; the end result is cell death. Energy-demanding neurons and vestibulocochlear hair cells are vulnerable to mitochondrial dysfunction, and hearing impairment and deafness are characteristic of neurodegenerative mitochondrial disease phenotypes. Beyond acting as cellular powerhouses, mitochondria regulate immune responses to infections, and studies of this phenomenon have aided in identifying nuclear factor kappa B and nuclear factor erythroid 2-related factor 2/antioxidant response element signaling as targets for discovery of otologic drugs, respectively, suppressing or upregulating these pathways. Treatment with free radical scavenging antioxidants is one therapeutic approach, with lipoic acid and corresponding carnitine esters exhibiting improved biodistribution and other features showing promise. These compounds are also histone deacetylase (HDAC) inhibitors, adding epigenetic modulation to the mechanistic milieu through which they act. These data suggest that new drugs targeting mitochondrial dysfunction and modulating epigenetic pathways via HDAC inhibition or other mechanisms hold great promise.
Harrar DB, Solomon J, Shah AS, Vaughn J, Durbin AD, Rivkin MJ. Diffusion-Weighted Imaging Changes in a Child With Posterior Ischemic Optic Neuropathy. Pediatr Neurol 2018;84:49-52.Abstract
BACKGROUND: Posterior ischemic optic neuropathy results from ischemia of the retrobulbar aspect of the optic nerve. It presents as acute loss of vision without optic disc swelling. This is rare in children, with only seven cases reported to date. Neuroimaging is frequently used to aid in the diagnosis of acute visual complaints in children; however, none of the cases described to date delineate the neuroimaging findings of this entity in children. METHODS: We retrospectively reviewed the electronic medical record. RESULTS: We describe the MRI findings in a 10-month-old boy with posterior ischemic optic neuropathy after intraophthalmic artery injection of chemotherapy for retinoblastoma. CONCLUSIONS: As targeted therapies for retinoblastoma and other diseases amenable to intravascular treatment delivery are more frequently used, the risk of grave vision-related side effects increases. Posterior ischemic optic neuropathy should be considered in the differential diagnosis of any child presenting with acute loss of vision. Dedicated imaging of the orbits can elucidate specific findings that may aid in the diagnosis of this entity in children.
Tsoka P, Matsumoto H, Maidana DE, Kataoka K, Naoumidi I, Gravanis A, Vavvas DG, Tsilimbaris MK. Effects of BNN27, a novel C17-spiroepoxy steroid derivative, on experimental retinal detachment-induced photoreceptor cell death. Sci Rep 2018;8(1):10661.Abstract
Retinal detachment (RD) leads to photoreceptor cell death secondary to the physical separation of the retina from the underlying retinal pigment epithelium. Intensifying photoreceptor survival in the detached retina could be remarkably favorable for many retinopathies in which RD can be seen. BNN27, a blood-brain barrier (BBB)-permeable, C17-spiroepoxy derivative of dehydroepiandrosterone (DHEA) has shown promising neuroprotective activity through interaction with nerve growth factor receptors, TrkA and p75. Here, we administered BNN27 systemically in a murine model of RD. TUNEL photoreceptors were significantly decreased 24 hours post injury after a single administration of 200 mg/kg BNN27. Furthermore, BNN27 increased inflammatory cell infiltration, as well as, two markers of gliosis 24 hours post RD. However, single or multiple doses of BNN27 were not able to protect the overall survival of photoreceptors 7 days post injury. Additionally, BNN27 did not induce the activation/phosphorylation of TrkA in the detached retina although the mRNA levels of the receptor were increased in the photoreceptors post injury. Together, these findings, do not demonstrate neuroprotective activity of BNN27 in experimentally-induced RD. Further studies are needed in order to elucidate the paradox/contradiction of these results and the mechanism of action of BNN27 in this model of photoreceptor cell damage.
Huang C-C, Yang W, Guo C, Jiang H, Li F, Xiao M, Davidson S, Yu G, Duan B, Huang T, Huang AJW, Liu Q. Anatomical and functional dichotomy of ocular itch and pain. Nat Med 2018;Abstract
Itch and pain are refractory symptoms of many ocular conditions. Ocular itch is generated mainly in the conjunctiva and is absent from the cornea. In contrast, most ocular pain arises from the cornea. However, the underlying mechanisms remain unknown. Using genetic axonal tracing approaches, we discover distinct sensory innervation patterns between the conjunctiva and cornea. Further genetic and functional analyses in rodent models show that a subset of conjunctival-selective sensory fibers marked by MrgprA3 expression, rather than corneal sensory fibers, mediates ocular itch. Importantly, the actions of both histamine and nonhistamine pruritogens converge onto this unique subset of conjunctiva sensory fibers and enable them to play a key role in mediating itch associated with allergic conjunctivitis. This is distinct from skin itch, in which discrete populations of sensory neurons cooperate to carry itch. Finally, we provide proof of concept that selective silencing of conjunctiva itch-sensing fibers by pruritogen-mediated entry of sodium channel blocker QX-314 is a feasible therapeutic strategy to treat ocular itch in mice. Itch-sensing fibers also innervate the human conjunctiva and allow pharmacological silencing using QX-314. Our results cast new light on the neural mechanisms of ocular itch and open a new avenue for developing therapeutic strategies.
Cestari DM, Freire MV, Chun BY. Vertical rectus muscle recession versus combined vertical and horizontal rectus muscle recession in patients with thyroid eye disease and hypotropia. J AAPOS 2018;Abstract
PURPOSE: To compare the postoperative vertical drift in patients with thyroid eye disease (TED) with hypotropia who underwent vertical rectus recession alone versus recession combined with horizontal rectus recession. METHODS: The medical records of patients with TED who underwent strabismus surgery for hypotropia between 2006 and 2015 were reviewed retrospectively. Patients were divided into two groups: group 1 underwent vertical rectus recession only; group 2 underwent vertical rectus recession plus horizontal rectus recession. Data collection included pre- and postoperative deviation measurements and amount of surgical recession performed. The amount of postoperative vertical drift between groups was compared. RESULTS: Of 67 patients who underwent surgery during the study period, 18 met inclusion criteria, 9 in each group. Mean postoperative hypotropia was 24.2 in group 1 and 24.5 in group 2 (P = 0.82). Mean vertical deviations were 0.3 and -2.2 (P = 0.134) on postoperative day 1 -0.9 and -8.0 (P = 0.043) at final follow-up for groups 1 and 2. Mean postoperative vertical drift toward hypertropia was 1.2 in group 1 and 6.8 in group 2 (P = 0.048). The surgical success rate for group 1 was superior to that for group 2 (89% vs 67% [P = 0.024]). CONCLUSIONS: There was a significantly larger postoperative vertical drift in TED patients with hypotropia who had combined vertical rectus and horizontal rectus recessions compared with those who underwent vertical rectus recession alone.
Wiggs JL, Kang JH, Fan BJ, Levkovitch-Verbin H, Pasquale LR. A Role for Clusterin in Exfoliation Syndrome and Exfoliation Glaucoma?. J Glaucoma 2018;27 Suppl 1:S61-S66.Abstract
The multifunctional protein clusterin (CLU) is a secreted glycoprotein ubiquitously expressed throughout the body, including in the eye. Its primary function is to act as an extracellular molecular chaperone, preventing the precipitation and aggregation of misfolded extracellular proteins. Clusterin is commonly identified at fluid-tissue interfaces, and has been identified in most body fluids. It is a component of exfoliation material, and CLU mRNA is reduced in eyes with exfoliation syndrome compared with controls. SNPs located in the CLU genomic region have been associated with Alzheimer disease (AD) at the genome-wide level and several CLU SNPs located in an apparent regulatory region have been nominally associated with XFS/XFG in Caucasians with European ancestry and in south Indians. Interestingly, clusterin associates with altered elastic fibers in human photoaged skin and prevents UV-induced elastin aggregation in vitro. In light of the known geographic risk factors for XFS/XFG, which could include UV light, investigations of CLU-geographic interactions could be of interest. Future studies investigating rare CLU variation and other complex interactions including gene-gene interactions in XFS/XFG cases and controls may also be fruitful. Although CLU has been considered as a therapeutic target in AD, cancer and dry eye, a role for clusterin in XFS/XFG needs to be better defined before therapeutic approaches involving CLU can be entertained.
Laíns I, Kelly RS, Miller JB, Vavvas DG, Kim IK, Lasky-Su J, Miller JW, Husain D. Reply. Ophthalmology 2018;125(7):e46-e47.
Guo X, Sriram S, Tran JA, Hutcheon AEK, Zieske JD. Inhibition of Human Corneal Myofibroblast Formation. Invest Ophthalmol Vis Sci 2018;59(8):3511-3520.Abstract
Purpose: Transforming growth factor-beta (TGF-β) isoform 1 (T1) is involved in corneal fibrotic wound healing by stimulating myofibroblast transformation and altering fibrotic gene expression. In this study, two specific inhibitors were used to dissect the relationship between myofibroblast generation and the TGF-β/Smad- or TGF-β/p38-signaling pathway in human corneal fibroblasts (HCF). Methods: In HCF, Trx-SARA (Smad-pathway inhibitor) was used to block the TGF-β/Smad-signaling pathway, and the p38 inhibitor (p38inh, SB202190) was used to inhibit p38MAPK, thus blocking the TGF-β/p38-signaling pathway. HCF ± Trx-SARA or Trx-GA (SARA control) were serum starved overnight in Eagle's minimum essential medium (EMEM) ± p38inh, grown in EMEM ± T1 ± p38inh for 24 hours, and then processed for indirect-immunofluorescence, Western blot, or quantitative real-time polymerase chain reaction to examine α-smooth muscle actin (αSMA) and other fibrotic genes, such as fibronectin, thrombospondin1, and type III collagen. In addition, the morphology and the effect of p38inh on myofibroblast phenotype after myofibroblast formation were examined. Results: We observed that Trx-SARA had little effect on αSMA expression, indicating that blocking the Smad pathway did not significantly inhibit myofibroblast formation. However, p38inh did significantly inhibit αSMA and other fibrotic genes, thus efficiently preventing the transition of HCFs to myofibroblasts. In addition, morphology changed and αSMA decreased in myofibroblasts exposed to p38inh medium, as compared with controls. Conclusions: HCF transition to myofibroblasts was mainly through the p38 pathway. Therefore, blocking the p38 pathway may be a potential therapeutic tool for human corneal fibrosis prevention/treatment, because it controls myofibroblast formation in human corneal cells, while leaving other functions of T1 unaffected.
Okunuki Y, Mukai R, Pearsall EA, Klokman G, Husain D, Park D-H, Korobkina E, Weiner HL, Butovsky O, Ksander BR, Miller JW, Connor KM. Microglia inhibit photoreceptor cell death and regulate immune cell infiltration in response to retinal detachment. Proc Natl Acad Sci U S A 2018;115(27):E6264-E6273.Abstract
Retinal detachment (RD) is a sight-threatening complication common in many highly prevalent retinal disorders. RD rapidly leads to photoreceptor cell death beginning within 12 h following detachment. In patients with sustained RD, progressive visual decline due to photoreceptor cell death is common, leading to significant and permanent loss of vision. Microglia are the resident immune cells of the central nervous system, including the retina, and function in the homeostatic maintenance of the neuro-retinal microenvironment. It is known that microglia become activated and change their morphology in retinal diseases. However, the function of activated microglia in RD is incompletely understood, in part because of the lack of microglia-specific markers. Here, using the newly identified microglia marker P2ry12 and microglial depletion strategies, we demonstrate that retinal microglia are rapidly activated in response to RD and migrate into the injured area within 24 h post-RD, where they closely associate with infiltrating macrophages, a population distinct from microglia. Once in the injured photoreceptor layer, activated microglia can be observed to contain autofluorescence within their cell bodies, suggesting they function to phagocytose injured or dying photoreceptors. Depletion of retinal microglia results in increased disease severity and inhibition of macrophage infiltration, suggesting that microglia are involved in regulating neuroinflammation in the retina. Our work identifies that microglia mediate photoreceptor survival in RD and suggests that this effect may be due to microglial regulation of immune cells and photoreceptor phagocytosis.
Singh AK, Phillips F, Merabet LB, Sinha P. Why Does the Cortex Reorganize after Sensory Loss?. Trends Cogn Sci 2018;22(7):569-582.Abstract
A growing body of evidence demonstrates that the brain can reorganize dramatically following sensory loss. Although the existence of such neuroplastic crossmodal changes is not in doubt, the functional significance of these changes remains unclear. The dominant belief is that reorganization is compensatory. However, results thus far do not unequivocally indicate that sensory deprivation results in markedly enhanced abilities in other senses. Here, we consider alternative reasons besides sensory compensation that might drive the brain to reorganize after sensory loss. One such possibility is that the cortex reorganizes not to confer functional benefits, but to avoid undesirable physiological consequences of sensory deafferentation. Empirical assessment of the validity of this and other possibilities defines a rich program for future research.

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