Cholesterol Sulfate in Biological Membranes: A Biophysical Study in Cholesterol-Poor and Cholesterol-Rich Biomimetic Models

As a surface-located molecule in biological membranes, cholesterol sulphate (CholS) plays a major role in membrane-driven cell-cell processes and events including platelet-cell adhesion, T-cell receptor signalling, sperm-egg interaction, membrane fusion, and skin differentiation. Despite this, little is known about the biophysical implications of CholS at the membrane in cells and organelles. In this study, we investigate the effect of increasing the content of CholS on the biophysical properties in cholesterol-poor and cholesterol-rich biomimetic models. Data obtained show that increasing amounts of CholS result in a slight increase in anisotropy, evidence for decreased membrane fluidity at higher CholS content (10 mol%) in cholesterol-poor systems but only negligible in rigidified epithelial-like cholesterol-rich systems. On the other hand, incorporation of CholS has an overall increasing ordering effect on membrane organisation and on-surface potential that is influenced by the lipid composition and cholesterol content. Though further research is needed to gain better insights on the (patho)physiological levels of CholS in cells and organelles, our findings are discussed in the context of diet-microbiota-host interactions in membrane-driven events in inflammatory-related disorders.