Phytosterol-mediated disturbance of the lipid packing order in the plasma membrane regulates inflammatory response.

While phytosterols have been widely reported for their anti-inflammatory effects, the precise biophysical mechanisms underlying their regulation of inflammatory responses remain largely unexplored. Our study demonstrates that phytosterols exhibit anti-inflammation effects in a structure-independent way. Quantitative analyses confirm that phytosterols are incorporated into lipid bilayers with varying efficacy, significantly disrupting the lipid packing order and mechanical properties of the cell membrane. This structural perturbation impairs the translocation of the p67^phox subunit to the cell membrane, thereby inhibiting the activity of NADPH oxidase (NOX). Consequently, this leads to a reduction in NOX-mediated reactive oxygen species (ROS) production and subsequent downregulation of NLRP3 inflammasome expression. Simulation results indicate that the incorporation of phytosterols increases the distance between adjacent molecules in the phospholipid bilayer, which may represent a potential mechanism underlying the increased fluidity of the cell membrane. In summary, this work provides novel insights into the bioactivity of phytosterols and highlights the significance of the physical properties of the cell membrane in regulating cellular activity.