Bilateral Cataract Induced by Unilateral UVR-B Exposure- Evidence for an Inflammatory Response

Abstract

Purpose: : To investigate if unilateral in vivo UVR-B exposure of one eye affects the contralateral eye in a co-cataractogenic, sympathetic reaction and to determine if an inflammatory response is involved in the pathogenesis.

Methods: : Eighty C57BL/6 mice were divided into four dose groups (n=20). Depending on dose group animals were unilaterally exposed in vivo to UVR-B for 15 minutes to 0x/ 2x/ 3x/ or 4x cataract threshold dose (MTD2.3:16) UVR-B. The radiation output of the UVR- source had lMAX at 302.6 nm with 4.5 nm [FWHM]. 48 hours following UVR - B exposure cataract was quantified as lens light scattering in the exposed and the contralateral not exposed lenses with a light dissemination meter. Cataract morphology was documented using dark field illumination photography. Serum levels of pro-inflammatory cytokines IL-1ß, IL-6 and TNF-α were measured with ELISA. Immunohistochemistry was performed for neutrophiles and macrophages with antibodies F4/80 and RB6-8C5 in exposed and contralateral eyes.

Results: : Exposed lenses scattered light higher than non-exposed lenses. The difference was significant at 2 & 4 MTD2.3:16 exposure dose. Mean light scattering in contralateral lenses in 2/ 3/ 4 MTD group was increased as compared to the control group(95% CI for mean light scattering in contralateral eyes:0 MTD= 0.227+/- 0.02 tEDC; 2 MTD= 0.261 +/- 0.02 tEDC; 3 MTD = 0.303 +/- 0.04 tEDC; 4 MTD= 0.319 +/- 0.04 tEDC). Serum pro-inflammatory cytokine levels were increased for IL-1β, IL-6 but not for TNF-α Inflammatory infiltration was detected with immunohistochemistry in the anterior segment of exposed eyes as well as in some mice also in the non-exposed eye.

Conclusions: : Unilateral UVR-B exposure increases light scattering also in the contralateral eye and triggers a systemic inflammatory response mediated by IL-1β and IL-6. Age related cataract is almost exclusively a bilateral event. Since a systemic response might be an important factor in the pathogenesis of the disease our results might initiate new approaches in cataract research.

Keywords: cataract • oxidation/oxidative or free radical damage • inflammation