Synchrotron-based FTIR microspectroscopy of protein aggregation and lipids peroxidation changes in human cataractous lens epithelial cells

Martin Kreuzer,Tanja Dučić,Sofija Andjelic,Marko Hawlina

doi:10.1038/s41598-020-72413-9

Abstract

Cataract is the leading cause of blindness worldwide but the mechanisms involved in the process of cataractogenesis are not yet fully understood. Two most prevalent types of age-related cataracts are nuclear (N) and cortical (C) cataracts. A common environmental factor in most age-related cataracts is believed to be oxidative stress. The lens epithelium, the first physical and biological barrier in the lens, is build from lens epithelial cells (LECs). LECs are important for the maintenance of lens transparency as they control energy production, antioxidative mechanisms and biochemical transport for the whole lens. The purpose of this study is to characterize compounds in LECs originated from N and C cataracts, by using the synchrotron radiation-based Fourier Transform Infrared (SR-FTIR) microspectroscopy, in order to understand the functional importance of their different bio-macromolecules in cataractogenesis. We used the SR-FTIR microspectroscopy setup installed on the beamline MIRAS at the Spanish synchrotron light source ALBA, where measurements were set to achieve single cell resolution, with high spectral stability and high photon flux. The results showed that protein aggregation in form of fibrils was notably pronounced in LECs of N cataracts, while oxidative stress and the lipids peroxidation were more pronounced in LECs of C cataracts.

Highlights

Cataract that can be defined as any opacity of the crystalline lens is the leading cause of blindness worldwide accounting for 48% of all causes of blindness
We found that protein aggregation in a form of fibrils is associated with N cataract type lens epithelial cells (LECs), while the oxidative stress and the lipids peroxidation were more pronounced in C cataract type LECs
We present an interconnection between damage of the lens epithelium cells and the developmental types of lens opacities, and the correlation with changes on the level of the essential bio-macromolecules

Summary

Introduction

Cataract that can be defined as any opacity of the crystalline lens is the leading cause of blindness worldwide accounting for 48% of all causes of blindness. Reactivity induce oxidative damage of fiber-cell membranes and proteins of the lens, beginning the progression of age-related c ataract[8,9]. The lipids peroxidation, the oxidative degradation of lipids, which can be initiated by increase of oxygen free radicals in the eye fluids and tissues and reduced lens antioxidant defences, may lead to cataractogenesis[10]. Lens lipid composition alters importantly in cataract[11] These changes could lead to crystalline structure of the lens, disturbed with age, the oxidative damage accumulates in the lens, which decrease turnover of lipids or proteins in the lens[12,13]. LECs high metabolic activity makes them subject to oxidative damage, and in UV-induced lens damage one of the early events is the lens epithelial lipid oxidation[15]. LECs are equipped with machinery to combat with cataractogenic insults, any alteration in the lens epithelium may proceed further in the remaining part of the lens and may lead to c ataract[21]

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