Zhuyu Pills promote polarization of macrophages toward M2 phenotype to prevent atherosclerosis via PPARγ/NF-κB signaling pathway

Abstract

This article aims to investigate the effect of Zhuyu Pills on atherosclerosis and decipher the underlying mechanism. The mouse model of atherosclerosis was induced by a high-fat diet, and the total modeling period was 12 weeks. A total of 47 ApoE~(-/-) mice successfully modeled were randomized into 5 groups, including 10 in the model group, 9 in each of low-, medium-, and high-dose(130.54, 261.08 and 522.16 mg·kg~(-1)·d~(-1), respectively) Zhuyu Pills groups, and 10 in the atorvastatin calcium(10.40 mg·kg~(-1)·d~(-1)) group. In addition, 10 C57BL/6J mice were included as the normal group. The mice in the normal group and model group were administrated with an equal volume of sterile distilled water, and those in other groups with corresponding agents by gavage once a day for 12 weeks. At the end of drug intervention, the levels of total cholesterol(TC), triglyceride(TG), high-density lipoprotein cholesterol(HDL-C), and low-density lipoprotein cholesterol(LDL-C) were measured by the biochemical method. Hematoxylin-eosin(HE) staining was employed to observe the plaque distribution in the aortic region. The serum levels of pro-inflammatory cytokines tumor necrosis factor-α(TNF-α) and interleukin(IL)-6 in M1 macrophages and anti-inflammatory cytokines IL-13 and IL-4 in M2 macrophages were determined by enzyme-linked immunosorbent assay(ELISA). The expression levels of inducible nitric oxide synthase(iNOS) and arginase-1(Arg-1) were examined by immunofluorescence. Real-time fluorescence quantitative polymerase chain reaction(real-time PCR) was employed to measure the mRNA levels of peroxisome proliferator-activated receptor γ(PPARγ), nuclear factor-κB(NF-κB), Arg-1, and iNOS in the aorta. Western blot was employed to determine the protein levels of PPARγ and NF-κB in the aorta. The results showed that compared with the normal group, the modeling elevated the TC, TG, and LDL-C levels, lowered the HDL-C level, caused large area thickening of the aortic intima, elevated the TNF-α and IL-6 levels, lowered the IL-4 and IL-13 levels, down-regulated the mRNA and protein levels of PPARγ and Arg-1, and up-regulated the mRNA and protein levels of iNOS and NF-κB in the aorta(P<0.01). Compared with the model group, low-, medium-, and high-dose Zhuyu Pills and atorvastatin calcium lowered the TC, TG, and LDL-C levels, elevated the HDL-C level, reduced the plaque area in a concentration-dependent manner, lowered the TNF-α and IL-6 levels, elevated the IL-4 and IL-13 levels, up-regulated the mRNA and protein levels of PPARγ and Arg-1, and down-regulated the mRNA and protein levels of NF-κB and iNOS in the aorta(P<0.05 or P<0.01). In conclusion, Zhuyu Pills may play an anti-atherosclerosis role by regulating PPARγ/NF-κB signaling pathway, inhibiting the polarization of macrophages toward the M1 phenotype, promoting the polarization of macrophages toward the M2 phenotype, and improving the inflammatory microenvironment of macrophages.