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Erschienen in:
01.05.2003 | Laboratory Investigation
Advanced glycation endproducts in human diabetic and non-diabetic cataractous lenses
Erschienen in: Graefe's Archive for Clinical and Experimental Ophthalmology | Ausgabe 5/2003
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Background
Advanced glycation endproduct (AGE) formation is thought to contribute to aging and cataract formation in the lens. In this study, we evaluated AGE immunoreactivity in human diabetic (n=14) and nondiabetic (n=31) cataractous lenses in relation to high-molecular-weight (HMW) protein content, which is believed to contribute to the onset of cataract.
Methods
AGE immunoreactivity was detected in alkali-soluble individual lens samples. Competitive ELISA with polyclonal anti-AGE antibody was performed to estimate AGEs. SDS-PAGE was used to detect changes in lens protein composition on the basis of molecular size.
Results
Regression analysis of data from nondiabetic lenses showed a significant correlation between lens AGE content and patient age (r=0.665, P<0.001). The curve exhibited exponential regression (y=0.272·e0.025x
). The level of nonspecified AGEs measured in diabetic lenses showed an overall increase compared with nondiabetic lenses (4.03±1.85 vs 1.78±0.71 AU/mg protein, P<0.0078). SDS-PAGE showed the occurrence of HMW proteins in both diabetic and nondiabetic lens samples. However, in diabetic patients, who had a higher level of AGEs, a significantly higher proportion of HMW proteins was also observed. The levels of AGE and percent of HMW aggregates showed a very significant correlation (r=0.68, P<0.007) in the diabetic group, whereas in nondiabetics the correlation, although positive, did not reach statistical significance.
Conclusion
The AGE distribution, with a higher proportion in the samples of lenses rich in HMW aggregates, corroborates the hypothesis that the advanced glycation process might have a role in degenerative changes in eye lens, which in diabetic patients occur vigorously and much earlier than in those without diabetes.