Black mulberry ethanol extract attenuates atherosclerosis-related inflammatory factors and downregulates PPARγ and CD36 genes in experimental atherosclerotic rats

Abstract

Atherosclerosis (AS) is the pathological basis of various vascular diseases and currently is seriously affecting human health. Numerous studies have paid more attention to natural medicines with anti-AS properties. As a traditional Uygur folk medicine, black mulberry fruits are conventionally used in the prevention and treatment of cardiovascular diseases in southern Xinjiang of China, and their underlying mechanisms remain unknown. Our previous study revealed that the ethanol extract of black mulberry (EEBM) inhibited AS development by improving lipid metabolism abnormalities, enhancing anti-oxidative activities, and reducing atherosclerotic lesions of atherosclerotic rats. Based on this, our objective was to further investigate the effects of EEBM on the expression of AS-related inflammatory factors and the key genes PPARγ and CD36 of the ox-LDL-PPARγ-CD36 feed-forward cycle in experimental atherosclerotic rats. Black mulberry fruits were extracted with acid ethanol and chromatographed on an AB-8 macroporous resin to obtain EEBM. All experimental rats were randomly divided into five groups: normal, model, model plus simvastatin (5 mg/kg d·body weight), and model plus low-dose and high-dose EEBM groups (105 and 210 mg/kg d·body weight, respectively). Serum levels of the inflammatory factors were determined by enzyme-linked immunosorbent assay (ELISA). The mRNA and protein expression of PPARγ and CD36 in atherosclerotic rats’ liver tissue and thoracic aorta were determined by Q-PCR and western blot analysis, respectively. EEBM at high dose effectively attenuated the abnormally expressed AS-related inflammatory factors of TNF-α, IL-6, MMP-9, and CRP in atherosclerotic rats by 41.5%, 66.1%, 77.5%, and 79.5%, respectively. After treatment with high dose EEBM, the elevated-expressions of PPARγ and CD36 at the mRNA and protein levels in atherosclerotic rats were found to be obviously downregulated at both levels. These results demonstrate that EEBM might lessen the AS-related inflammatory reaction, and then inhibit the formation of ox-LDL, consequently downregulating the expression of PPARγ and CD36 at the mRNA and protein levels, thus reducing macrophage-foam-cell formation and prohibiting the development of atherosclerotic plaque through the ox-LDL-PPARγ-CD36 feed-forward cycle, which can effectively prevent the occurrence and development of AS in atherosclerotic rats.