Mechanisms of Ocular Toxicity Using the in Vitro Bovine Lens and Sodium Dodecyl Sulfate as a Chemical Model

Abstract

Previous work using the in vitro bovine lens as a model has shown a correlation between toxicity and lens optical function and showed much higher sensitivity in detecting irritancy of several surfactants at much lower concentrations than the Draize score. In the current study, cultured bovine lenses were used to study the effects of the surfactant sodium dodecyl sulfate (SDS) on lens optical properties and mitochondrial integrity. Bovine lenses were exposed to SDS (0.1 to 0.00625%) for 30 min and cultured for 24 h. Compared to controls (n = 17), loss of sharp focus was evident immediately following exposure to 0.1% SDS (n = 14, p < 0.0001). At 24 h loss of sharp focus became evident in all groups. Loss of lens transparency, significant increase in lens wet weight, and axial length were seen 24 h postexposure in lenses treated with 0.1 to 0.025% SDS. Confocal analysis 24 h postexposure showed SDS concentration-dependent decrease in number and length of the mitochondria in lens epithelial and superficial cortical fiber cells. The results of this study show a correlation between lens optical properties and metabolic function and together provide a sensitive in vitro model of ocular chemical toxicity. Results of confocal analysis suggest that the mitochondrial integrity of the superficial cortical fiber cells is most sensitive to damage caused by SDS. The results further suggest that recovery of lens metabolic function is necessary for the recovery of lens optical properties.

Lipids and the ocular lens

“…Maintaining low levels of oxygen is critical to the lens to prevent oxidation and opacifi cation. One of the roles of the mitochondria, located in the epithelium and outer cortical fi bers (204)(205)(206)(207)(208), is to degrade oxygen ( 209 ). The cholesterol-related impermeability of the membranes to Fig.…”

Biocompatibility of Contact Lens Solutions Using Confocal Laser Scanning Microscopy and the In Vitro Bovine Cornea

“…Although the significance of the accumulation of the mitochondria around the nuclei in intermediate and basal cells is not clear, similar distributions of mitochondria were shown in the chick 22 and primate 23 lens epithelium and in the rat, 24 fish, 25 guinea pig, 26 and cow 6,27,28 lens. This is also true of work in other laboratories on HeLa human cervical carcinoma cells or 143B human osteosarcoma cells.…”

“…The third stage was noted in lenses treated with the highest concentrations of SDS, in which rhodamine 123 fluorescence was not seen, indicating the absence of metabolically active mitochondria in the lens epithelial and superficial cortical fiber cells. 6 These results indicate that mitochondria are sensitive indicators of mild ocular irritation, and changes in their phenotype can be used as a biomarker. Transferring this approach from the lens to the cornea in monitoring changes in mitochondrial phenotype in cells of the central corneal epithelium by using fresh bovine corneas can potentially become useful in the process of developing or screening ophthalmic solutions.…”

“…The heterogeneous phenotype of the mitochondria consists of structures that ranged from less than 1 m in size to threads longer than 10 m. The mitochondria of the intermediate layers appeared more numerous and denser than those of the superficial and basal epithelium (Figs. [3][4][5]. From more than 430 highresolution, individual, X,Y images taken at 0.44-m Z step, a three-dimensional image of the entire thickness of the corneal epithelium was reconstructed (Fig.…”

“…4 A recent study using confocal laser scanning microscopy and the in vitro bovine lens 5 showed a strong correlation between changes in the distribution, number, and size of the mitochondria and the concentration of potentially eye-irritating chemicals. In this study, besides some nuclear modification seen in bovine lens epithelial cells associated with sodium dodecyl sulfate (SDS) treatment, a most significant triphase structural change was observed in the mitochondria.…”