Irritating effects of sodium lauryl sulfate on human primary keratinocytes at subtoxic levels of exposure

Abstract

Chemical agents that can potentially cause skin irritation are typically tested in animal models or in vitro assays of cell viability or cytokine expression. However, these methods do not always provide translatable results and are not sufficiently sensitive for subtoxicity detection. Here, we introduce the mechanical properties of keratinocytes as novel endpoints for the safety assessment of chemical agents at the subtoxicity level. Human primary keratinocytes were treated with various concentrations of sodium lauryl sulfate (SLS) and their biological properties (proliferation, membrane integrity, inflammatory response, and morphology) were observed. Their biomechanical and geometrical parameters (stiffness and surface roughness) were also investigated by atomic force microscopy. Keratinocyte morphophysiological changes and inflammatory responses were significant at ≥25 μM SLS. The keratinocytes became less stiff due to changes in the distribution of F-actin filaments and α-tubulin; these changes were significant even at lower doses of SLS (≤10 μM). The morphophysiological changes of keratinocytes were clearly seen at a relatively high dose of SLS, while the mechanical properties of keratinocytes responded linearly to SLS at lower doses. Therefore, changes in mechanical properties can be used as new endpoints for in vitro toxicity testing with keratinocytes. K E Y W O R D S atomic force microscopy, human primary keratinocyte, irritants, mechanical properties, safety assessment

The Number of Ethylene Oxide Groups of Sulphate-Based Surfactants Influences the Cytotoxicity of Mixed Micelles to an Amphibian Cell Line

“…Bjerregaard et al [37] using the same cellular model, A6 cell line, demonstrated that LAS was able to activate calcium channels in the apical membrane and destabilize ion homeostasis, contributing to a higher chloride secretion due to the activation of calcium-dependent chloride channels from the apical membrane [37]. Alterations to calcium metabolism induced by sodium lauryl sulphate (SLS) at concentrations higher than 7.21 mg/L (converted from the original result of 25 µM reported in the article) were also found in keratinocytes and in a reconstructed human epidermal skin model [38]. Mizutani et al [39] demonstrated that membrane damage due to SLE 0 S activates calcium channels, inducing an increase in intracellular calcium promoting the formation of ROS and the activation of IL-1, leading to skin roughness.…”

“…Vater et al [36] showed that human keratinocytes and fibroblasts cell lines, when exposed to 1.65 mg/L of SLE 0 S (converted from the original result of 5% concentration reported in their article), have no active metabolism and, therefore, no viability after 24 h of exposure, with our work demonstrating far lower concentrations for LC 90 , but this higher cytotoxicity may be due to the presence of LAS. Several studies focusing on the effect of SLE n S and LAS in keratinocytes and other cellular models demonstrate that the exerted cytotoxic effects are not exclusive to membrane damage but also involve the formation of reactive oxygen species (ROS) together with altered calcium metabolism [37][38][39]. Bjerregaard et al [37] using the same cellular model, A6 cell line, demonstrated that LAS was able to activate calcium channels in the apical membrane and destabilize ion homeostasis, contributing to a higher chloride secretion due to the activation of calcium-dependent chloride channels from the apical membrane [37].…”

The Design and Optimization of Ceramide NP-Loaded Liposomes to Restore the Skin Barrier

“…Even the CER-NP, oleic acid, and cholesterol are naturally bio-transformed through the skin surface; the concentration of skin lipids in the formulation can cause skin irritation. To work the safety assessment, the liposomes without CER-NP and the optimized CER-NP-loaded liposomes were applied to the keratinocyte cell line in comparison with SLS as positive control, which is acceptable as cytotoxic on human keratinocytes within each concentration used in this study [ 67 , 68 ].…”

Characterization of ionic liquid cytotoxicity mechanisms in human keratinocytes compared with conventional biocides

“…These include the effect of heavy metal ions (Holmes et al, 2020(Holmes et al, , 2016Orlowski et al, 2016), surfactants and pharmaceuticals (Abruzzo et al, 2017;Choi et al, 2018;Kim et al, 2019;Sugita et al, 2017), as well as antimicrobial agents (Kim et al, 2008;Lam et al, 2020;Pulingam et al, 2020) and wound sensor materials (Bhushan et al, 2019). In addition, the human keratinocyte cells lines NCTC 2544 and HaCat have previously been used to evaluate ultra-short antimicrobial peptides (Pasupuleti et al, 2009).…”