Comparison of cytotoxicity effects induced by four different types of nanoparticles in human corneal and conjunctival epithelial cells

Xiangzhe Li,Boram Kang,Jong Suk Song,Hyo Myung Kim,Hyung Keun Lee,Jingxiang Zhong,Youngsub Eom

doi:10.1038/s41598-021-04199-3

Abstract

The impact of particulate matter (PM) on ocular surface health has attracted increased attention in recent years. Previous studies have reported that differences in the chemical composition of PM can affect the toxicological response. However, available information on the toxic effects of chemical components of PM on the ocular surface is insufficient. In this paper, we aimed to investigate the toxicity effects of chemical components of PM on the ocular surface, focusing on the effects of four different types of nanoparticles (NPs) in human corneal epithelial cells (HCECs) and human conjunctival epithelial cells (HCjECs), which include titanium dioxide (TiO2), carbon black (CB), zinc dioxide (ZnO), and silicon dioxide (SiO2). We found that the in vitro cytotoxic effects of CB, ZnO, and SiO2 NPs are dependent on particle properties and cell type as well as the exposure concentration and time. Here, the order of increasing toxicity was SiO2 → CB → ZnO, while TiO2 demonstrated no toxicity. Moreover, toxic effects appearing more severe in HCECs than HCjECs. Reactive oxygen species (ROS)-mediated oxidative stress plays a key role in the toxicity of these three NPs in HCECs and HCjECs, leading to apoptosis and mitochondrial damage, which are also important contributors to aging. Sirtuin1 (SIRT1) as an NAD+-dependent protein deacetylase that seems to play a potential protective role in this process. These findings implied that ROS and/or SIRT1 may become a potential target of clinical treatment of PM- or NP-related ocular surface diseases.

Highlights

The impact of particulate matter (PM) on ocular surface health has attracted increased attention in recent years
We found that cell toxicity is dependent on exposure concentration, particle properties, and cell type
After 24 h of exposure at varying doses (12.5, 25, 50, 100, 200, and 400 μg/mL) of TiO2, carbon black (CB), zinc dioxide (ZnO), and S iO2 NPs, the cell viability of human corneal epithelial cells (HCECs) and human conjunctival epithelial cells (HCjECs) as detected by the Water-soluble tetrazolium salt (WST)-8 assay resulted in explicit dose-dependent reductions, excluding TiO2 NPs (Fig. 1A,B)

Summary

Introduction

The impact of particulate matter (PM) on ocular surface health has attracted increased attention in recent years. We aimed to investigate the toxicity effects of chemical components of PM on the ocular surface, focusing on the effects of four different types of nanoparticles (NPs) in human corneal epithelial cells (HCECs) and human conjunctival epithelial cells (HCjECs), which include titanium dioxide (TiO2), carbon black (CB), zinc dioxide (ZnO), and silicon dioxide (SiO2). SIRT1 is an NAD+-dependent protein deacetylase that has been linked to various physiological and pathological processes and conditions, including DNA repair, aging, cellular senescence, oxidative stress, inflammation, and mitochondrial function[27,28,29,30,31]. To evaluate the different effects of chemical components of PM on the ocular surface, this study conducted a systematic and comparative investigation of the toxicity effects of four different NPs ( TiO2, CB, ZnO, and SiO2) on HCECs and human conjunctival epithelial cells (HCjECs). The expression of SIRT1 as well as ROS generation, apoptosis, and mitochondrial function were investigated

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Conclusion