Simvastatin preparations promote PDGF-BB secretion to repair LPS-induced endothelial injury through the PDGFRβ/PI3K/Akt/IQGAP1 signalling pathway

Endothelial barrier dysfunction is a critical pathophysiological process of sepsis. Impaired endothelial cell migration is one of the main reasons for endothelial dysfunction. Statins may have a protective effect on endothelial barrier function. However, the effect and mechanism of statins on lipopolysaccharide (LPS)-induced endothelial barrier dysfunction remain unclear. Simvastatin (SV) was loaded in nanostructured lipid carriers to produce SV nanoparticles (SV-NPs). Normal SV and SV-NPs were used to treat human umbilical vein vascular endothelial cells (HUVECs) injured by LPS. Barrier function was evaluated by monitoring cell monolayer permeability and transendothelial electrical resistance, and cell migration ability was measured by a wound healing assay. LY294002 and imatinib were used to inhibit the activity of PI3K/Akt and platelet-derived growth factor receptor (PDGFR) beta. IQ-GTPase-activating protein 1 (IQGAP1) siRNA was used to knockdown endogenous IQGAP1, which was used to verify the role of the PDGFR beta/PI3K/Akt/IQGAP1 pathway in SV/SV-NPs-mediated barrier protection in HUVECs injured by LPS. The results show that SV/SV-NPs promoted the migration and decreased the permeability of HUVECs treated with LPS, and the efficacy of the SV-NPs exceeded that of SV significantly. LY294002, imatinib and IQGAP1 siRNA all suppressed the barrier protection of SV/SV-NPs. SV/SV-NPs promoted the secretion of platelet-derived growth factor-BB (PDGF-BB) and activated the PDGFR beta/PI3K/Akt/IQGAP1 pathway. SV preparations restored endothelial barrier function by restoring endothelial cell migration, which is involved in the regulation of the PDGFR beta/PI3K/Akt/IQGAP1 pathway and PDGF-BB secretion. As an appropriate formulation for restoring endothelial dysfunction, SV-NPs may be more effective than SV.