Sinomenine protects endothelial cells from ox-LDL injury by regulating MEF2A/CXCL14 pathway, reducing inflammation and pyroptosis.

Atherosclerosis (AS) is a leading cause of mortality, characterized by chronic inflammation and lipid deposition in arterial walls, primarily initiated by endothelial injury. Current therapeutic strategies often fall short in simultaneously addressing lipid deposition, chronic inflammation, and endothelial dysfunction. Oxidized low-density lipoprotein (ox-LDL) is a key instigator of endothelial cell damage, triggering oxidative stress, inflammation, and a specific form of programmed cell death called pyroptosis. Sinomenine (SIN), a natural alkaloid, has shown promise in delaying AS progression by attenuating endothelial inflammation, but its precise mechanism against ox-LDL-induced endothelial injury, particularly concerning pyroptosis and macrophage polarization, remained to be fully elucidated.

Researchers established an in vitro model of atherosclerosis using human umbilical vein endothelial cells (HUVECs) exposed to ox-LDL to induce injury. These injured HUVECs were then treated with Sinomenine. Cell viability was assessed using CCK-8 assays. Oxidative stress markers (ROS, SOD, MDA) and inflammatory cytokines (TNF-α, IL-β, IL-6) were quantified with commercial kits. Protein levels of pyroptosis-related markers (NLRP3, ASC, activated caspase-1, GSDMD-N), and macrophage polarization markers (Arg1, CD206, iNOS, CXCL14, MEF2A) were determined via Western blot. CXCL14 mRNA expression was measured by RT-qPCR. The direct binding of MEF2A to the CXCL14 promoter was confirmed using dual-luciferase reporter and ChIP assays, further investigating the mechanistic pathway.

Sinomenine treatment significantly alleviated ox-LDL-caused oxidative stress, inflammation, pyroptosis, and M1 macrophage polarization in HUVECs. Specifically, Sinomenine treatment reduced the generation of reactive oxygen species (ROS) and malondialdehyde (MDA), while increasing superoxide dismutase (SOD) activity, indicating a mitigation of oxidative stress. It also suppressed the release of pro-inflammatory cytokines TNF-α, IL-β, and IL-6. Furthermore, Sinomenine effectively decreased the protein levels of pyroptosis-associated markers, including NLRP3, ASC, activated caspase-1, and GSDMD-N. The study also observed a shift in macrophage polarization markers, with increased Arg1 and CD206 (M2 markers) and decreased iNOS (M1 marker) in HUVECs. Crucially, silencing either CXCL14 or MEF2A abolished the protective effects of Sinomenine on ox-LDL-induced HUVEC injury. Mechanistically, MEF2A was found to directly interact with the CXCL14 promoter, promoting its transcription, a pathway that Sinomenine treatment restrained in the context of ox-LDL-evoked injury. > Sinomenine treatment restrained ox-LDL-evoked HUVEC injury and M1 macrophage polarization partly via targeting the MEF2A/CXCL14 axis.