Cellular Response and Reactive Hyaluronan Production in UV-Exposed Rabbit Corneas

Podskochy, Alexander; Fagerholm, Per

doi:10.1097/00003226-199811000-00012

Cited by 29 publications

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“…Then, the medium was replaced with HBSS containing 0.1% FBS and cells were submitted for 36 s at room temperature to UV exposure (Vilber Lourmat Lamp, Cedex, France: wavelength range set at 280-350 nm and peak at 312 nm), receiving in these conditions a total equivalent energy of 80 mJ/cm 2 under constant intensity. This energy dosage was chosen since in-between to the energy quoted in vivo to induce keratitis (140 mJ/cm 2 ) and subkeratitis (30 mJ/cm 2 ) [6]. After 3 h, the medium was further substituted and SIRCs were incubated for 18 h in a medium containing 10% FBS in the absence (control) or presence of aforesaid substances.…”

Section: Irradiation With Uv-b Rays Of Sircmentioning

confidence: 99%

“…Indeed, the effect of UV light has been extensively investigated [1][2][3][4][5][6][7][8]. It has been reported that biotoxic epiphenomena may take place when the threshold level of radiation absorbed in corneal tissues is exceeded, and, consequently, permanent keratocyte damage or loss, epithelium destruction, endothelium edema and necrosis occur, as well as biochemical changes, such as ROS production, protein cross-linking, enzyme inactivation, DNA strand breaks and chemotactic factor release [9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

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Antioxidant protection in cultured corneal cells and whole corneas submitted to UV-B exposure

Ciuffi

Pisanello

Pagliai

et al. 2003

Journal of Photochemistry and Photobiology B: Biology

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Several corneal pathologies are characterized by the presence of reactive oxygen species (ROS); therefore, we evaluated the protection afforded by pirenoxine and melatonin to corneal cell culture and whole rabbit cornea from ultraviolet exposure and other oxidant systems.Rabbit cornea cell (SIRC) plates and whole corneas were exposed to UV-B (80 or 800 mJ/cm 2 ) or incubated with fMLPstimulated autologous macrophages, in the presence or absence of pirenoxine or melatonin (10 À5 M). The protective activity of compounds was assessed by measuring superoxide anion formation, inhibition of oxidation and mitochondrial viability. Moreover the ex vivo protective effect of pirenoxine and melatonin was verified in the whole cornea submitted to UV-B exposure in vitro.Our experimental data demonstrate that pirenoxine and melatonin were able to inhibit the superoxide formation and oxidative effect in cell culture and whole rabbit corneas submitted to UV-B exposure or to incubation with fMLP-stimulated autologous macrophages.Mitochondrial viability was restored in epithelial cells of rabbit cornea but not in SIRCs. Moreover, both compounds are also able to increase ex vivo epithelial corneal cell defences against the in vitro UV-B induced lipid peroxidation.

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Section: Irradiation With Uv-b Rays Of Sircmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Antioxidant protection in cultured corneal cells and whole corneas submitted to UV-B exposure

Ciuffi

Pisanello

Pagliai

et al. 2003

Journal of Photochemistry and Photobiology B: Biology

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“…8,10 However, this is not to be expected because the keratocyte loss can be repaired rapidly by repopulation from migrating keratocytes of the adjacent cornea. 8,22 Loss of keratocytes has been observed already in other corneal procedures without having dramatic consequences. So after PRK, 8 LASIK, 8,9 or epithelial injury 10-12 keratocyte apoptosis of variable degree was described.…”

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confidence: 99%

Keratocyte cytotoxicity of riboflavin/UVA-treatment in vitro

Wollensak

Spoerl

Reber

et al. 2004

Eye

241

183

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Purpose Collagen crosslinking using ultraviolet-A (UVA) -irradiation combined with the photosensitizer riboflavin is a new technique for treating progressive keratoconus. It has been shown to increase effectively the biomechanical strength of the cornea and to stop or even reverse the progression of keratoconus. As part of a safety evaluation, the present study was undertaken to investigate in vitro the possible cytotoxic effect of combined riboflavin/UVA-treatment on corneal keratocytes and to compare it to UVA-irradiation alone. Methods Cell cultures established from porcine keratocytes were treated with 0.025% riboflavin solution and various UVA (370 nm)-irradiances ranging from 0.4 to 1.0 mW/cm 2 and with UVA alone between 2 and 9 mW/cm 2 for 30 min. The cell cultures were evaluated for cell death 24 h after irradiation using trypanblue and Yopro-fluorescence staining. Results An abrupt cytotoxic irradiance level was found at 0.5 mW/cm 2 for keratocytes after UVA-irradiation combined with the photosensitizer riboflavin, which is 10-fold lower than the cytotoxic irradiance of 5 mW/ cm 2 after UVA-irradiation alone. Conclusions A cytotoxic effect of combined riboflavin/UVA-treatment on keratocytes is to be expected at 0.5 mW/cm 2 , which is reached in the clinical setting in human corneas down to a depth of 300 mm using the standard surface UVA-irradiance of 3 mW/cm 2 .

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“…The peak of apoptosis occurs at approximately 24 hours after UVR exposure (Podskochy et al 2000). Following the initial corneal injury, cells surrounding the damaged tissues start to produce hyaluronan (HA) (Podskochy & Fagerholm 1998). HA staining is only seen in association with migrating keratocytes and no deposits of significance are seen.…”

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confidence: 99%

Repeated UVR exposures cause keratocyte resistance to apoptosis and hyaluronan accumulation in the rabbit cornea

Podskochy

Fagerholm

2001

Acta Ophthalmologica Scandinavica

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ABSTRACT.Purpose: To evaluate hyaluronan (HA) production and level of apoptosis of corneal cells after repeated UVR exposures. Methods: Fifteen albino rabbit corneas were exposed to 310 nm UVR at a dose that causes biomicroscopically significant keratitis (0.47 J/cm 2 ). Nine rabbits received a single dose of UVR. Six rabbits were irradiated 3 times at 7-day intervals. Rabbits exposed to the single dose of UVR, were sacrificed 24 hours, 7 and 14 days after irradiation. Rabbits exposed to the repeated doses of UVR, were sacrificed 24 hours and 14 days after the last irradiation. The corneal tissue specimens were processed for histological analysis using specific staining for HA, and the TdT-dUTP terminal nick-end labeling (TUNEL) assay. Results: Corneas exposed to a single UVR dose showed extensive positive TU-NEL staining 24 hours after exposure. Almost all basal epithelial cells, keratocytes throughout the entire thickness of the stroma, and endothelial cells were TUNEL-positive. No HA was found 24 hours after exposure. Extracellular HA staining of high intensity was found at day 7 throughout the entire central stroma, except the anterior one-fourth. At day 14 only a faint HA staining was detected in the posterior stroma, close to Descemet's membrane. Corneas exposed to repeated UVR doses showed at 24 hours positive TUNEL staining only in epithelial cells and in very few stromal cells. The majority of stromal cells and endothelial cells were unaffected. At the same time HA staining of very high intensity was found both at 24 hours and day 14, and it was evenly distributed throughout the entire thickness of the stroma. Conclusion: Repeated UVR exposures lead to increased production and accumulation of HA in the corneal stroma. The repopulated keratocytes are much more resistant to apoptosis than the native ones. HA accumulation may be a sign of long-term changes in the cornea.

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Cellular Response and Reactive Hyaluronan Production in UV-Exposed Rabbit Corneas

Cited by 29 publications

References 0 publications

Antioxidant protection in cultured corneal cells and whole corneas submitted to UV-B exposure

Antioxidant protection in cultured corneal cells and whole corneas submitted to UV-B exposure

Keratocyte cytotoxicity of riboflavin/UVA-treatment in vitro

Repeated UVR exposures cause keratocyte resistance to apoptosis and hyaluronan accumulation in the rabbit cornea

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