Mechanism of scutellarein inhibiting foaming of macrophages by promoting cholesterol efflux pathway / 中国药理学通报

Aim To investigate the effects of scutellarein on the macrophage foam cell formation and cholesterol efflux, and the underlying mechanism. Methods THP-1 cells were differentiated with PMA, and the cell viability was detected by MTT assays. The effects of scutellarein on the cholesterol efflux and macrophage foam cell formation were evaluated by using NBD-la-beled cholesterol and the cholesterol detection kit. The effects of scutellarein on the activation of PPARγ-LXRα-ABCA1 signaling pathway were determined by molecular docking, ELISA, dual-luciferase reporter and Western blot. The effects of PPARγ knowdown on scutellarein-induced cholesterol efflux and inhibiting macrophage foaming were analyzed by siRNA interference. Results Scutellarein dose-dependently inhibited oxLDL-induced cholesterol accumulation, accelerated cholesterol efflux and significantly increased the protein expression of LXRα and ABCA1. At the same time, scutellarein could bind PPARγ and initiate its downstream LXRa-ABCAl signaling pathway. In addition, gene silencing of PPARγ not only significantly inhibited scutellarein-induced LXRα-ABCA1 signaling pathway and cholesterol efflux, but also reversed the inhibitory effect of scutellarein on macrophage foaming. Conclusions Scutellarein could promote the cholesterol efflux by activating PPARγ and initiating the downstream LXR-ABCA1 signaling pathway, thereby prevent the macrophage foam cell formation.

The effect of PPARγ-ABCA1 pathway on Chlamydia pneumoniaeindnced foam cell formation / 中华微生物学和免疫学杂志

Objective To investigate the mechanisms of Chlamydia pneumoniae (C. pn)-induced foam cell formation, the expression of ATP binding cassette transporter AI ( ABCA1 ) and perexisome prolif-erator-activated receptor γ (PPARγ) were examined. Methods THP-1 monneytes were induced into mac-rophages after the addition of 160 nmol/L phorbol myristate acetate (PMA) for 72 h. THP-1-dorived macro-phages when co-cuhured 50 mg/L low density lipoprotein (LDL) were designated randomly in four groups: control (uninfected) group, C. pn infection group, rosiglitazone + C. pn infection group and rosiglitazone group. Lipid droplets in cytoplasm were observed by oil red O staining. The contents of intracellnlur choles-terol ester were detected by enzyme-flnoreseence. The expression of ABCA1, PPARγ, mRNA and protein were determined by RT-PCR and Western blot, respectively. Results C. pn down-regulated the expression of ABCA1, PPARγ at mRNA and protein levels in a concentration-dependent manner in THP-1-derived mac-rophages when co-incubated with LDL. Resiglitazone not only concentration-dependently alleviated the down-regulation of ABCA1 expression by C. pn infection (P<0.05), but also markedly suppressed the accumula- tion of lipid droplets and cholesteryl ester by C. pn at higher concentrations ( 10 and 20 μaol/L). Condu-sion C. pn induces foam cell formation by down-regulating the expression of ABCA1 via PPART pathway, which may provide a new evidence for the development and progression of atherosclerosis initiated by C. pn infection.