Publications

2014

Schaumberg D, Rose L, Deangelis M, Semba R, Hageman G, Chasman D. Prospective study of common variants in CX3CR1 and risk of macular degeneration: pooled analysis from 5 long-term studies. JAMA Ophthalmol. 2014;132(1):84–95.
IMPORTANCE: The CX3CR1 gene is implicated as a candidate gene for age-related macular degeneration (AMD) through several lines of evidence. There is uncertainty, however, as to whether common genetic variants in CX3CR1 alter risk of AMD, since prior studies have been inconsistent and mostly limited to evaluation of 2 nonsynonymous variants, T280M (rs3732378) and V249I (rs3732379). OBJECTIVE: To determine if common variants in CX3CR1 predict future risk of AMD. DESIGN, SETTING, AND PARTICIPANTS: Prospective nested case-control study within 5 large study populations with long-term follow-up. We measured genotypes for T280M, V249I, and 13 other common single-nucleotide polymorphisms (SNPs) of the CX3CR1 gene among people who developed AMD (n = 1110, including 369 with neovascular AMD) and 2532 age- and sex-matched controls. MAIN OUTCOMES AND MEASURES: We determined the incidence rate ratios (RR) and 95% CIs for incidence of AMD for each variant and examined interactions with other AMD-associated variants and modifiable risk factors. RESULTS: In additive genetic models, we identified nonsignificant associations with AMD for T280M (RR, 0.87; P = .07) and 3 other SNPs, rs2853707 (RR, 0.88; P = .07), rs12636547 (RR, 0.85; P = .10), and rs1877563 (RR, 0.84; P = .06), 1 of which, rs2853707, is positioned in the CX3CR1 promoter region and was associated with neovascular AMD (RR, 0.75; P = .03). We observed that a recessive model was a better fit to the data for some SNPs, with associations between rs11715522 and AMD (RR, 1.27; P = .03) and between rs2669845 (RR, 3.10; P = .04), rs2853707 (RR, 0.48; P = .050), and rs9868689 (RR, 0.31; P = .02) and neovascular AMD. Moreover, in exploratory analyses, we identified a number of possible interactions including between V249I and rs2669845 and dietary intake of ω-3 fatty acids (P = .004 and P = .009, respectively) for AMD; between rs2669845 and obesity (P = .03) for neovascular AMD; between T280M and complement component 3 (C3) R102G for AMD (P = .03); between rs2669845 and Y402H in complement factor H for AMD (P = .04); and between rs2669845, rs2853707, and V249I and C3 R102G for neovascular AMD (P = .008; .04; and .002, respectively). CONCLUSIONS AND RELEVANCE: This study failed to identify significant associations between common CX3CR1 variants and AMD after considering the number of SNPs analyzed and multiple comparisons. However, we observed evidence consistent with recessive modes of association and that an effect of CX3CR1 variants may depend on other factors including dietary intake of ω-3 fatty acids, obesity, and genotypes at CFH Y402H and C3 R102G. If replicated in other populations, these findings would support a role for CX3CR1 in AMD but also suggest that its role may involve mechanisms that are independent of the T280M/V249I variations.
Seo, Ji, Lee, Shim, Noh, Yeo, Park, Park, Chang, Lee. Activation of HIF-1α (hypoxia inducible factor-1α) prevents dry eye-induced acinar cell death in the lacrimal gland. Cell Death Dis. 2014;5:e1309.
The pathogenesis of immune-mediated lacrimal gland (LG) dysfunction in Sjögren's syndrome has been thoroughly studied. However, the majority of dry eye (DE) is not related to Sjögren type, and its pathophysiology remains unclear. The purpose of this study was to determine and investigate the protective mechanisms against DE stress in mice. DE induced prominent blood vessel loss without apoptosis or necrosis in the LG. Autophagic vacuoles, distressed mitochondria, and stressed endoplasmic reticulum were observed via electron microscopy. Immunoblotting confirmed the increase in autophagic markers. Glycolytic activities were enhanced with increasing levels of succinate and malate that, in turn, activated hypoxia-inducible factor (HIF)-1α. Interestingly, the areas of stable HIF-1α expression overlapped with COX-2 and MMP-9 upregulation in LGs of DE-induced mice. We generated HIF-1α conditional knockout (CKO) mice in which HIF-1α expression was lost in the LG. Surprisingly, normal LG polarities and morphologies were completely lost with DE induction, and tremendous acinar cell apoptosis was observed. Similar to Sjögren's syndrome, CD3(+) and CD11b(+) cells infiltrated HIF-1α CKO LGs. Our results show that DE induced the expression of HIF-1α that activated autophagy signals to prevent further acinar cell damage and to maintain normal LG function.
Shao Z, Fu Z, Stahl A, Joyal JS, Hatton C, Juan A, Hurst C, Evans L, Cui Z, Pei D, Gong Y, Xu D, Tian K, Bogardus H, Edin M, Lih F, Sapieha P, Chen J, Panigrahy D, Hellström A, Zeldin D, Smith L. Cytochrome P450 2C8 ω3-long-chain polyunsaturated fatty acid metabolites increase mouse retinal pathologic neovascularization--brief report. Arterioscler Thromb Vasc Biol. 2014;34(3):581–6.
OBJECTIVE: Regulation of angiogenesis is critical for many diseases. Specifically, pathological retinal neovascularization, a major cause of blindness, is suppressed with dietary ω3-long-chain polyunsaturated fatty acids (ω3LCPUFAs) through antiangiogenic metabolites of cyclooxygenase and lipoxygenase. Cytochrome P450 epoxygenases (CYP2C8) also metabolize LCPUFAs, producing bioactive epoxides, which are inactivated by soluble epoxide hydrolase (sEH) to transdihydrodiols. The effect of these enzymes and their metabolites on neovascularization is unknown. APPROACH AND RESULTS: The mouse model of oxygen-induced retinopathy was used to investigate retinal neovascularization. We found that CYP2C (localized in wild-type monocytes/macrophages) is upregulated in oxygen-induced retinopathy, whereas sEH is suppressed, resulting in an increased retinal epoxide:diol ratio. With a ω3LCPUFA-enriched diet, retinal neovascularization increases in Tie2-driven human-CYP2C8-overexpressing mice (Tie2-CYP2C8-Tg), associated with increased plasma 19,20-epoxydocosapentaenoic acid and retinal epoxide:diol ratio. 19,20-Epoxydocosapentaenoic acids and the epoxide:diol ratio are decreased with overexpression of sEH (Tie2-sEH-Tg). Overexpression of CYP2C8 or sEH in mice does not change normal retinal vascular development compared with their wild-type littermate controls. The proangiogenic role in retina of CYP2C8 with both ω3LCPUFA and ω6LCPUFA and antiangiogenic role of sEH in ω3LCPUFA metabolism were corroborated in aortic ring assays. CONCLUSIONS: Our results suggest that CYP2C ω3LCPUFA metabolites promote retinal pathological angiogenesis. CYP2C8 is part of a novel lipid metabolic pathway influencing retinal neovascularization.
Sharma R, Makino C, Hicks D, Duda T. ROS-GC interlocked Ca(2+)-sensor S100B protein signaling in cone photoreceptors: review. Front Mol Neurosci. 2014;7:21.
Photoreceptor rod outer segment membrane guanylate cyclase (ROS-GC) is central to visual transduction; it generates cyclic GMP, the second messenger of the photon signal. Photoexcited rhodopsin initiates a biochemical cascade that leads to a drop in the intracellular level of cyclic GMP and closure of cyclic nucleotide gated ion channels. Recovery of the photoresponse requires resynthesis of cyclic GMP, typically by a pair of ROS-GCs, 1 and 2. In rods, ROS-GCs exist as complexes with guanylate cyclase activating proteins (GCAPs), which are Ca(2+)-sensing elements. There is a light-induced fall in intracellular Ca(2+). As Ca(2+) dissociates from GCAPs in the 20-200 nM range, ROS-GC activity rises to quicken the photoresponse recovery. GCAPs then progressively turn down ROS-GC activity as Ca(2+) and cyclic GMP levels return to baseline. To date, GCAPs mediate the only known mechanism of ROS-GC regulation in the photoreceptors. However, in mammalian cone outer segments, cone synapses and ON bipolar cells, another Ca(2+) sensor protein, S100B, complexes with ROS-GC1 and senses the Ca(2+) signal with a K1/2 of 400 nM. Unlike GCAPs, S100B stimulates ROS-GC activity when Ca(2+) is bound. Thus, the ROS-GC system in cones functions as a Ca(2+) bimodal switch; with rising intracellular Ca(2+), its activity is first turned down by GCAPs and then turned up by S100B. This presentation provides a historical perspective on the role of S100B in the photoreceptors, offers a pictorial model for the "bimodal" operation of the ROS-GC switch and projects future tasks that are needed to understand its operation. Some accounts of this review have been adopted from the original publications of these authors.
Singer J, Kreiman G. Short temporal asynchrony disrupts visual object recognition. J Vis. 2014;14(5):7.
Humans can recognize objects and scenes in a small fraction of a second. The cascade of signals underlying rapid recognition might be disrupted by temporally jittering different parts of complex objects. Here we investigated the time course over which shape information can be integrated to allow for recognition of complex objects. We presented fragments of object images in an asynchronous fashion and behaviorally evaluated categorization performance. We observed that visual recognition was significantly disrupted by asynchronies of approximately 30 ms, suggesting that spatiotemporal integration begins to break down with even small deviations from simultaneity. However, moderate temporal asynchrony did not completely obliterate recognition; in fact, integration of visual shape information persisted even with an asynchrony of 100 ms. We describe the data with a concise model based on the dynamic reduction of uncertainty about what image was presented. These results emphasize the importance of timing in visual processing and provide strong constraints for the development of dynamical models of visual shape recognition.
Age-related macular degeneration (AMD) is a common cause of irreversible visual loss and the disease burden is rising world-wide as the population ages. Both environmental and genetic factors contribute to the development of this disease. Among environmental factors, smoking, obesity and dietary factors including antioxidants and dietary fat intake influence onset and progression of AMD. There are also several lines of evidence that link cardiovascular, immune and inflammatory biomarkers to AMD. The genetic etiology of AMD has been and continues to be an intense and fruitful area of investigation. Genome-wide association studies have revealed numerous common variants associated with AMD and sequencing is increasing our knowledge of how rare genetic variants strongly impact disease. Evidence for interactions between environmental, therapeutic and genetic factors is emerging and elucidating the mechanisms of this interplay remains a major challenge in the field. Genotype-phenotype associations are evolving. The knowledge of non-genetic, modifiable risk factors along with information about heritability and genetic risk variants for this disease acquired over the past 25 years have greatly improved patient management and our ability to predict which patients will develop or progress to advanced forms of AMD. Personalized medicine and individualized prevention and treatment strategies may become a reality in the near future.
Stepp MA, Zieske J, Trinkaus-Randall V, Kyne B, Pal-Ghosh S, Tadvalkar G, Pajoohesh-Ganji A. Wounding the cornea to learn how it heals. Exp Eye Res. 2014;121:178–93.
Corneal wound healing studies have a long history and rich literature that describes the data obtained over the past 70 years using many different species of animals and methods of injury. These studies have lead to reduced suffering and provided clues to treatments that are now helping patients live more productive lives. In spite of the progress made, further research is required since blindness and reduced quality of life due to corneal scarring still happens. The purpose of this review is to summarize what is known about different types of wound and animal models used to study corneal wound healing. The subject of corneal wound healing is broad and includes chemical and mechanical wound models. This review focuses on mechanical injury models involving debridement and keratectomy wounds to reflect the authors' expertise.
Stevenson W, Sadrai Z, Hua J, Kodati S, Huang JF, Chauhan S, Dana R. Effects of topical Janus kinase inhibition on ocular surface inflammation and immunity. Cornea. 2014;33(2):177–83.
PURPOSE: To determine the effects of topical Janus kinase inhibition on ocular surface inflammation and immunity. METHODS: Ophthalmic 0.003% tofacitinib (CP-690,550) was administered topically to inhibit Janus kinase activation at the ocular surface. Male BALB/c mice 6 to 8 weeks of age were subjected to corneal thermocautery and randomized to receive tofacitinib, vehicle, or no treatment. Corneas were subsequently excised for fluorescence-activated cell sorting and quantitative real-time reverse transcription polymerase chain reaction. Female C57BL/6 mice 6 to 8 weeks of age were exposed to desiccating stress to induce experimental dry eye disease and randomized to receive tofacitinib, tofacitinib and vehicle, vehicle, or no treatment. Corneal fluorescein staining was performed to evaluate clinical disease severity. The corneas and conjunctivae were harvested for immunohistochemical staining and quantitative real-time reverse transcription polymerase chain reaction. RESULTS: After corneal thermocautery, it was found that tofacitinib treatment decreased the corneal infiltration of CD45+, Gr-1+, and CD11b+ cells on days 1 and 3. Transcripts encoding interleukin (IL)-1β and IL-6 were significantly decreased by tofacitinib treatment at post-thermocautery day 3. In experimental dry eye disease, tofacitinib treatment twice per day significantly decreased corneal fluorescein staining on days 12 and 15. The corneal infiltration of CD11b+ cells was significantly decreased by tofacitinib treatment twice per day. Tofacitinib treatment twice per day significantly increased the corneal expression of IL-1RA, and significantly decreased the corneal expression of tumor necrosis factor and IL-23. Further, tofacitinib treatment twice per day significantly decreased the conjunctival expression of IL-17A and significantly increased the conjunctival expression of FoxP3. CONCLUSIONS: Topical ophthalmic tofacitinib, a Janus kinase inhibitor, suppressed ocular surface inflammation and immunity in experimental corneal thermocautery and dry eye disease.
Suelves A, Siddique S, Schurko B, Foster S. Anterior chamber intraocular lens implantation in patients with a history of chronic uveitis: five-year follow-up. J Cataract Refract Surg. 2014;40(1):77–81.
PURPOSE: To compare the incidence of long-term complications after cataract surgery with primary anterior chamber intraocular lens (AC IOL) implantation in uveitic patients and patients without a history of intraocular inflammation (control group). SETTING: Single-center private practice. DESIGN: Retrospective clinical study. METHODS: The study comprised patients who between November 2005 and August 2010 had cataract extraction followed by AC IOL implantation because conventional placement was not possible. Outcome measures were the incidence of intraoperative and postoperative complications, preoperative corrected distance visual acuity (CDVA), and CDVA after 1 year. RESULTS: Of the 39 patients identified through electronic medical records, 17 (17 eyes) had a history of chronic uveitis and 22 (23 eyes) had no intraocular inflammatory disease. There were no significant differences in the incidence of intraoperative and postoperative complications between the 2 groups during follow-up (range 12 to 68 months) (P=.702). Although uveitic eyes had a greater risk for epiretinal membrane formation, the incidence of uveitis flareups attributed to the IOL and deposits on IOL surfaces was comparable to that in the control group (P<.001). The CDVA improved significantly in both groups 1 year after surgery (P<.01 and P<.001, respectively). CONCLUSION: In uveitic eyes with inadequate capsule support, AC IOL implantation restored visual function without a significant increase in long-term postoperative complications compared with eyes that had no history of uveitis.