Among the identified risk factors of age-related macular degeneration, sunlight is known to induce cumulative damage to the retina. A photosensitive derivative of the visual pigment, N-retinylidene-N-retinylethanolamine (A2E), may be involved in this phototoxicity. The high energy visible light between 380 nm and 500 nm (blue light) is incriminated. Our aim was to define the most toxic wavelengths in the blue-green range on an in vitro model of the disease. Primary cultures of porcine retinal pigment epithelium cells were incubated for 6 hours with different A2E concentrations and exposed for 18 hours to 10 nm illumination bands centered from 380 to 520 nm in 10 nm increments. Light irradiances were normalized with respect to the natural sunlight reaching the retina. Six hours after light exposure, cell viability, necrosis and apoptosis were assessed using the Apotox-Glo Triplex？ assay. Retinal pigment epithelium cells incubated with A2E displayed fluorescent bodies within the cytoplasm. Their absorption and emission spectra were similar to those of A2E. Exposure to 10 nm illumination bands induced a loss in cell viability with a dose dependence upon A2E concentrations. Irrespective of A2E concentration, the loss of cell viability was maximal for wavelengths from 415 to 455 nm. Cell viability decrease was correlated to an increase in cell apoptosis indicated by caspase-3/7 activities in the same spectral range. No light-elicited necrosis was measured as compared to control cells maintained in darkness. Our results defined the precise spectrum of light retinal toxicity in physiological irradiance conditions on an in vitro model of age-related macular degeneration. Surprisingly, a narrow bandwidth in blue light generated the greatest phototoxic risk to retinal pigment epithelium cells. This phototoxic spectrum may be advantageously valued in designing selective photoprotection ophthalmic filters, without disrupting essential visual and non-visual functions of the eye.
References
[1]
Congdon N, O'Colmain B, Klaver CC, Klein R, Munoz B, et al. (2004) Causes and prevalence of visual impairment among adults in the United States. Arch Ophthalmol 122: 477–485.
[2]
Friedman DS, O'Colmain BJ, Munoz B, Tomany SC, McCarty C, et al. (2004) Prevalence of age-related macular degeneration in the United States. Arch Ophthalmol 122: 564–572.
[3]
Rein DB, Wittenborn JS, Zhang X, Honeycutt AA, Lesesne SB, et al. (2009) Forecasting age-related macular degeneration through the year 2050: the potential impact of new treatments. Arch Ophthalmol 127: 533–540.
[4]
Smith W, Assink J, Klein R, Mitchell P, Klaver CC, et al. (2001) Risk factors for age-related macular degeneration: Pooled findings from three continents. Ophthalmology 108: 697–704.
[5]
Augood CA, Vingerling JR, de Jong PT, Chakravarthy U, Seland J, et al. (2006) Prevalence of age-related maculopathy in older Europeans: the European Eye Study (EUREYE). Arch Ophthalmol 124: 529–535.
[6]
Seddon JM, Reynolds R, Yu Y, Daly MJ, Rosner B (2012) Risk models for progression to advanced age-related macular degeneration using demographic, environmental, genetic, and ocular factors. Ophthalmology 118: 2203–2211.
[7]
Cruickshanks KJ, Klein R, Klein BE, Nondahl DM (2001) Sunlight and the 5-year incidence of early age-related maculopathy: the beaver dam eye study. Arch Ophthalmol 119: 246–250.
[8]
Taylor HR, West S, Munoz B, Rosenthal FS, Bressler SB, et al. (1992) The long-term effects of visible light on the eye. Arch Ophthalmol 110: 99–104.
[9]
Young RW (1992) Sunlight and age-related eye disease. J Natl Med Assoc 84: 353–358.
[10]
Mitchell P, Smith W, Wang JJ (1998) Iris color, skin sun sensitivity, and age-related maculopathy. The Blue Mountains Eye Study. Ophthalmology 105: 1359–1363.
[11]
Fletcher AE, Bentham GC, Agnew M, Young IS, Augood C, et al. (2008) Sunlight exposure, antioxidants, and age-related macular degeneration. Arch Ophthalmol 126: 1396–1403.
[12]
Butt AL, Lee ET, Klein R, Russell D, Ogola G, et al. (2011) Prevalence and risks factors of age-related macular degeneration in Oklahoma Indians: the Vision Keepers Study. Ophthalmology 118: 1380–1385.
[13]
Vojnikovic B, Synek S, Micovic V, Telezar M, Linsak Z (2010) Epidemiological study of sun exposure and visual field damage in children in Primorsko-Goranska County – the risk factors of earlier development of macular degeneration. Coll Antropol 34 Suppl 257–59.
[14]
Sui GY, Liu GC, Liu GY, Gao YY, Deng Y, et al. (2013) Is sunlight exposure a risk factor for age-related macular degeneration? A systematic review and meta-analysis. Br J Ophthalmol. 97: 389–394.
[15]
Klein R, Cruickshanks KJ, Nash SD, Krantz EM, Javier Nieto F, et al. (2010) The prevalence of age-related macular degeneration and associated risk factors. Arch Ophthalmol 128: 750–758.
[16]
Bazan HE, Bazan NG, Feeney-Burns L, Berman ER (1990) Lipids in human lipofuscin-enriched subcellular fractions of two age populations. Comparison with rod outer segments and neural retina. Invest Ophthalmol Vis Sci 31: 1433–1443.
Sparrow JR, Wu Y, Kim CY, Zhou J (2010) Phospholipid meets all-trans-retinal: the making of RPE bisretinoids. J Lipid Res 51: 247–261.
[19]
Ben-Shabat S, Itagaki Y, Jockusch S, Sparrow JR, Turro NJ, et al. (2002) Formation of a nonaoxirane from A2E, a lipofuscin fluorophore related to macular degeneration, and evidence of singlet oxygen involvement. Angew Chem Int Ed Engl 41: 814–817.
[20]
Parish CA, Hashimoto M, Nakanishi K, Dillon J, Sparrow J (1998) Isolation and one-step preparation of A2E and iso-A2E, fluorophores from human retinal pigment epithelium. Proc Natl Acad Sci U S A 95: 14609–14613.
[21]
Hunter JJ, Morgan JI, Merigan WH, Sliney DH, Sparrow JR, et al. (2012) The susceptibility of the retina to photochemical damage from visible light. Prog Retin Eye Res 31: 28–42.
[22]
Van Norren D, Gorgels TG (2011) The action spectrum of photochemical damage to the retina: a review of monochromatic threshold data. Photochem Photobiol 87: 747–753.
[23]
Lawwill T (1982) Three major pathologic processes caused by light in the primate retina: a search for mechanisms. Trans Am Ophthalmol Soc 80: 517–579.
[24]
Lund DJ, Stuck BE, Edsall P (2006) Retinal injury thresholds for blue wavelength lasers. Health Phys 90: 477–484.
[25]
Grimm C, Wenzel A, Williams T, Rol P, Hafezi F, et al. (2001) Rhodopsin-mediated blue-light damage to the rat retina: effect of photoreversal of bleaching. Invest Ophthalmol Vis Sci 42: 497–505.
[26]
Van Norren D, Schellekens P (1990) Blue light hazard in rat. Vision Res 30: 1517–1520.
[27]
Gorgels TG, van Norren D (1995) Ultraviolet and green light cause different types of damage in rat retina. Invest Ophthalmol Vis Sci 36: 851–863.
[28]
Putting BJ, Van Best JA, Vrensen GF, Oosterhuis JA (1994) Blue-light-induced dysfunction of the blood-retinal barrier at the pigment epithelium in albino versus pigmented rabbits. Exp Eye Res 58: 31–40.
[29]
Putting BJ, van Best JA, Zweypfenning RC, Vrensen GF, Oosterhuis JA (1993) Spectral sensitivity of the blood-retinal barrier at the pigment epithelium for blue light in the 400–500 nm range. Graefes Arch Clin Exp Ophthalmol 231: 600–606.
[30]
Putting BJ, Zweypfenning RC, Vrensen GF, Oosterhuis JA, van Best JA (1992) Blood-retinal barrier dysfunction at the pigment epithelium induced by blue light. Invest Ophthalmol Vis Sci 33: 3385–3393.
[31]
Putting BJ, Zweypfenning RC, Vrensen GF, Oosterhuis JA, van Best JA (1992) Dysfunction and repair of the blood-retina barrier following white light exposure: a fluorophotometric and histologic study. Exp Eye Res 54: 133–141.
[32]
Van Best JA, Putting BJ, Oosterhuis JA, Zweypfenning RC, Vrensen GF (1997) Function and morphology of the retinal pigment epithelium after light-induced damage. Microsc Res Tech 36: 77–88.
[33]
Wihlmark U, Wrigstad A, Roberg K, Nilsson SE, Brunk UT (1997) Lipofuscin accumulation in cultured retinal pigment epithelial cells causes enhanced sensitivity to blue light irradiation. Free Radic Biol Med 22: 1229–1234.
[34]
Davies S, Elliott MH, Floor E, Truscott TG, Zareba M, et al. (2001) Photocytotoxicity of lipofuscin in human retinal pigment epithelial cells. Free Radic Biol Med 31: 256–265.
[35]
Sparrow JR, Miller AS, Zhou J (2004) Blue light-absorbing intraocular lens and retinal pigment epithelium protection in vitro. J Cataract Refract Surg 30: 873–878.
[36]
Sparrow JR, Nakanishi K, Parish CA (2000) The lipofuscin fluorophore A2E mediates blue light-induced damage to retinal pigmented epithelial cells. Invest Ophthalmol Vis Sci 41: 1981–1989.
[37]
Sparrow JR, Parish CA, Hashimoto M, Nakanishi K (1999) A2E, a lipofuscin fluorophore, in human retinal pigmented epithelial cells in culture. Invest Ophthalmol Vis Sci 40: 2988–2995.
[38]
Schutt F, Davies S, Kopitz J, Holz FG, Boulton ME (2000) Photodamage to human RPE cells by A2-E, a retinoid component of lipofuscin. Invest Ophthalmol Vis Sci 41: 2303–2308.
[39]
Zhou J, Sparrow JR (2011) Light filtering in a retinal pigment epithelial cell culture model. Optom Vis Sci 88: 759–765.
[40]
Sparrow JR, Cai B (2001) Blue light-induced apoptosis of A2E-containing RPE: involvement of caspase-3 and protection by Bcl-2. Invest Ophthalmol Vis Sci 42: 1356–1362.
[41]
Westlund BS, Cai B, Zhou J, Sparrow JR (2009) Involvement of c-Abl, p53 and the MAP kinase JNK in the cell death program initiated in A2E-laden ARPE-19 cells by exposure to blue light. Apoptosis 14: 31–41.
[42]
Boettner EA, Wolter JR (1962) Transmission of the ocular media. Investigative Ophthalmology 1(6).
[43]
Sparrow JR, Zhou J, Ben-Shabat S, Vollmer H, Itagaki Y, et al. (2002) Involvement of oxidative mechanisms in blue-light-induced damage to A2E-laden RPE. Invest Ophthalmol Vis Sci 43: 1222–1227.
[44]
Hafezi F, Marti A, Munz K, Reme CE (1997) Light-induced apoptosis: differential timing in the retina and pigment epithelium. Exp Eye Res 64: 963–970.
[45]
Grimm C, Wenzel A, Hafezi F, Yu S, Redmond TM, et al. (2000) Protection of Rpe65-deficient mice identifies rhodopsin as a mediator of light-induced retinal degeneration. Nat Genet 25: 63–66.
[46]
Maiti P, Kong J, Kim SR, Sparrow JR, Allikmets R, et al. (2006) Small molecule RPE65 antagonists limit the visual cycle and prevent lipofuscin formation. Biochemistry 45: 852–860.
[47]
Maeda A, Golczak M, Maeda T, Palczewski K (2009) Limited roles of Rdh8, Rdh12, and Abca4 in all-trans-retinal clearance in mouse retina. Invest Ophthalmol Vis Sci 50: 5435–5443.
[48]
Maeda A, Maeda T, Golczak M, Palczewski K (2008) Retinopathy in mice induced by disrupted all-trans-retinal clearance. J Biol Chem 283: 26684–26693.
[49]
Maeda T, Maeda A, Matosky M, Okano K, Roos S, et al. (2009) Evaluation of potential therapies for a mouse model of human age-related macular degeneration caused by delayed all-trans-retinal clearance. Invest Ophthalmol Vis Sci 50: 4917–4925.
[50]
Kaya S, Weigert G, Pemp B, Sacu S, Werkmeister RM, et al. (2012) Comparison of macular pigment in patients with age-related macular degeneration and healthy control subjects – a study using spectral fundus reflectance. Acta Ophthalmol 90: e399–403.
[51]
Raman R, Rajan R, Biswas S, Vaitheeswaran K, Sharma T (2011) Macular pigment optical density in a South Indian population. Invest Ophthalmol Vis Sci 52: 7910–7916.
[52]
Gellermann W, Ermakov IV, Ermakova MR, McClane RW, Zhao DY, et al. (2002) In vivo resonant Raman measurement of macular carotenoid pigments in the young and the aging human retina. J Opt Soc Am A Opt Image Sci Vis 19: 1172–1186.
[53]
Sabour-Pickett S, Nolan JM, Loughman J, Beatty S (2012) A review of the evidence germane to the putative protective role of the macular carotenoids for age-related macular degeneration. Mol Nutr Food Res 56: 270–286.
[54]
Weigert G, Kaya S, Pemp B, Sacu S, Lasta M, et al. (2011) Effects of lutein supplementation on macular pigment optical density and visual acuity in patients with age-related macular degeneration. Invest Ophthalmol Vis Sci 52: 8174–8178.
[55]
Rezai KA, Gasyna E, Seagle BL, Norris JR Jr, Rezaei KA (2008) AcrySof Natural filter decreases blue light-induced apoptosis in human retinal pigment epithelium. Graefes Arch Clin Exp Ophthalmol 246: 671–676.
[56]
Sanchez-Ramos C, Vega JA, del Valle ME, Fernandez-Balbuena A, Bonnin-Arias C, et al. (2010) Role of metalloproteases in retinal degeneration induced by violet and blue light. Adv Exp Med Biol 664: 159–164.
[57]
Tanito M, Kaidzu S, Anderson RE (2006) Protective effects of soft acrylic yellow filter against blue light-induced retinal damage in rats. Exp Eye Res 83: 1493–1504.
[58]
Ueda T, Nakanishi-Ueda T, Yasuhara H, Koide R, Dawson WW (2009) Eye damage control by reduced blue illumination. Exp Eye Res 89: 863–868.
