In vitro Cytoprotective Study of Sunscreen Cream X on Hacat Cells Against Pollution Models

Abstract

The skin barrier function is constantly subject to external aggressions such as air pollution which induce important cell damages. Most environmental pollutants may undergo transformation through certain processes, mainly oxidation, into free radical species capable of inducing numerous toxic effects. Upon reaction between biomolecules in the skin and free radicals, in particular Reactive Oxygen Species (ROS), peroxides are formed. The process of oxidation and peroxides resulting from the reaction will induce oxidative stress that causes damage to cell structures and connective tissues which may ultimately lead to skin aging and skin diseases (Audina, 2021). In this study, the epidermal protective effect of sunscreen cream X against pollution was assessed on HaCaT cells by using H2O2 and CSE pollution models. More specifically, the cell viability of HaCaT cells exposed to the pollution models and treated with the sunscreen was measured using MTS assay and image analysis. Pollution stands as one of the major problems around the world that involve the introduction of harmful substances towards the environment and may negatively affect the quality of land, water, and also air. Among the other types of pollution, air pollution is reported to be the most significant cause of various health issues and even death (Dwi sutanto, 2020). Based on the World Health Organization (WHO), six major categories of air pollutants are particle pollution, ground-level ozone, carbon monoxide, nitrogen oxides, sulfur oxides, and heavy metals. Most environmental pollutants may undergo transformation through certain processes, mainly oxidation, into free radical species capable of inducing numerous toxic effects. The human skin, notably the upper epidermis layer, serves a crucial role as a barrier from the outside environment to fight off chemical and physical assaults and prevent pathogens invasion as well as excessive loss of solutes and water. However, it is also among the earliest and most vital targets of air pollutants (Drakaki, Dessinioti, & Antoniou, 2014). Upon reaction between biomolecules in the skin and free radicals, in particular Reactive Oxygen Species (ROS), peroxides are formed. The process of oxidation and peroxides resulting from the reaction will induce oxidative stress, the imbalance state between generation of ROS and antioxidant-mediated defense mechanisms. This causes damage to cell structures and connective tissues which ultimately may lead to skin aging and skin diseases like urticaria, psoriasis, and atopic dermatitis (Audina, 2021). Sunscreen cream X claims that it has the ability to protect the skin against free radicals by ingredients which act as antioxidants. In this research project, Sunscreen cream X will be tested on HaCaT (Immortalized human keratinocyte line) cells that compose around 95% of the skin epidermis, to determine whether it truly possesses the ability to fight free radicals or not. Several pollution models that are used in this project to test the product cover the hydrogen peroxide (H2O2) model and the cigarette smoke extract (CSE) model. The H2O2 model is used because it is easily accessible, cheap, and can be used at a wide range of pH and temperature (Simonenko, Gomonov, Rolle, & Molodkina, 2015). Uncontrolled exposure to ROS including H2O2 may cause oxidative stress which has the potential to damage biomolecules (Imlay, 2013). In addition, H2O2 exposure has been correlated to apoptosis and DNA damage via a mitochondrial pathway (Xiang et al., 2016). This model pathway serves as a representation of free radicals' effect on skin cells. Whereas, the CSE model is utilized because it is quite simple, and the materials needed to construct the model are inexpensive. Cigarette smoke is known to contain numerous chemicals such as nicotine, pesticide residues, metal-carbon monoxide, hydrogen cyanide, acrolein, ROS (superoxide, nitric oxide, H2O2), and many more which are released into the atmosphere as air pollutants (Bernard et al., 2019). Several components of cigarette smoke including ROS and acrolein may also induce oxidative stress that further damages the cells. This model employs CSE exposure against HaCaT cells in order to represent the effect of burning and smoke from air pollution on skin cells (Benedikter et al., 2017). Moreover, it allows the observation of the effect of direct H2O2 and cigarette smoke against HaCaT cells and whether both models will yield comparable results. The aim of the study is to measure cytoprotective capability of sunscreen cream X against pollution models such as cigarette smoke extract and H2O2 using HaCaT cells