Telomere‐dependent senescent phenotype of lens epithelial cells as a biological marker of aging and cataractogenesis: the role of oxidative stress intensity and specific mechanism of phospholipid hydroperoxide toxicity in lens and aqueous

Abstract

Cataract formation represents a serious problem in the elderly and has a large impact on healthcare budget. Aging and cataract formation are relatively complex phenomena, both in vivo and in vitro. Telomeres are special structures at the end of chromosomes. They shorten during each round of replication, and this has been characterized as a mitotic counting mechanism. Our review analysis in this work shows that the rate of telomere shortening in human lens epithelial cells during aging and cataract formation is modulated by oxidative stress as well as by differences in antioxidative defense capacity of the normal and cataractous crystalline lenses. Presented in this review studies suggest that telomere shortening in human lens cells and increased oxidative stress are the result of the peroxidative damage to the lens cell membranes and biomolecules induced in the lack of reductive detoxification of phospholipid hydroperoxides as the triggering mechanism of cataractogenesis. Lipid peroxidation (LPO) is a causative factor of cataract. The increased concentrations of primary molecular LPO products (diene conjugates, lipid hydroperoxides) and end fluorescent LPO products were detected in the lipid moieties of the aqueous humor samples obtained from patients with senile and complicated cataracts when compared to normal donors. The progressive accumulation of oxidative damage may act as an important mechanism for organism aging and cataractogenesis. The oxidative stress form and intensity might determine the lens senescence rate and cataract type, making efforts in the cataract prevention challenge more complex. The analyzed challenge in this work is that the reduction in telomere shortening rate and damages in telomeric DNA make an important contribution to the anticataract and life-extension effect of carnosine administered systemically in the formulations stabilizing a dipeptide from the enzymatic hydrolysis with carnosinase, or topically administered to the eye with carnosine ophthalmic prodrug N-acetylcarnosine and lubricant formulations thereof including corneal absorption promoters. Telomere length in the human crystalline lens cells is a reflection of aging, cataractogenesis, and lifespan in biogerontological studies.