Endocytic Mechanism of Internalization of Dietary Peptide Lunasin into Macrophages in Inflammatory Condition Associated with Cardiovascular Disease

Abstract

Cardiovascular disease (CVD) is the leading cause of death in the United States. Diet influences risk factors associated with CVD and atherosclerosis, a major vascular disease that arises from inflammation. Lunasin, a peptide derived from plant foods such as soybeans, contains a unique Arg-Gly-Asp cell-adhesion motif and inhibits the pathways involved in the inflammatory cascade. The objective was to determine the mechanism by which lunasin is internalized into human THP-1 macrophages, investigate the expression of endocytic membrane proteins in inflammatory conditions and to identify the pathways involved. While lipopolysaccharide (10 nM), vitronectin (130 nM) and a combination of these two molecules enhanced lunasin uptake and increased basal αVβ3 integrin expression, lunasin reduced αVβ3 expression by 25.5, 26.8 and 49.2%, respectively. The pretreatment of cells with brefeldin A (71 µM), an inhibitor of protein trafficking, inhibited lunasin internalization by up to 99.8%. Lunasin increased caveolin-1 expression by up to 204.8%, but did not modulate clathrin. The pretreatment of macrophages with nystatin (54 µM), an inhibitor of caveolae-dependent endocytosis, reduced lunasin internalization. The presence of amantadine (1 mM) and amiloride (1 mM), inhibitors of clathrin-mediated endocytosis and macropinocytosis, abolished lunasin cell entry. Lunasin elicited a transient reduction in intracellular levels of Ca2+ in LPS-induced macrophages. The results suggest that internalization of lunasin into macrophages is amplified in inflammatory conditions and is primarily mediated by endocytic mechanisms that involve integrin signaling, clathrin-coated structures and macropinosomes. Lunasin may be responsible for attenuation of CVD risk factors by interacting with pathways involved in endocytosis and inflammation.

Lunasin Attenuates Obesity-Associated Metastasis of 4T1 Breast Cancer Cell through Anti-Inflammatory Property

“…Galvez et al have demonstrated that lunasin was involved in decreasing the gene expression of hepatic 3-hydroxy-3-methyl-glutaryl (HMG) CoA reductase in HepG2 cells and increasing the expression of the low density lipoprotein (LDL) receptor [36,37]. Moreover, lunasin intervention repressed THP-1 macrophage inflammation by interacting with endocytosis pathways [38]. These studies supported that lunasin may contribute to prevent the cardiovascular disease procession.…”

Oral Administration of CardioAid and Lunasin Alleviates Liver Damage in a High-Fat Diet Nonalcoholic Steatohepatitis Model

“…Additionally, it has a direct antioxidant effect on enterocytes exposed to oxidizing species [6]. Lunasin has been suggested to be responsible for the attenuation of cardiovascular [37] risk factors by interacting with pathways involved in endocytosis and inflammation [38]. …”

Pepsin-pancreatin protein hydrolysates from extruded amaranth inhibit markers of atherosclerosis in LPS-induced THP-1 macrophages-like human cells by reducing expression of proteins in LOX-1 signaling pathway

“…There is a strong relationship between CVD and the diet [2]. The consumption of whole cereals, fruits and vegetables could help to reduce the risk to develop diseases such as obesity, diabetes, hypertension, which are related with the development of CVD, specifically atherosclerosis [3].…”