Evaluation of the Multifunctionality of Soybean Proteins and Peptides in Immune Cell Models

Abstract

Inflammatory and oxidative processes are tightly regulated by innate and adaptive immune systems, which are involved in the pathology of a diversity of chronic diseases. Soybean peptides, such as lunasin, have emerged as one of the most hopeful food-derived peptides with a positive impact on health. The aim was to study the potential antioxidant and immunomodulatory activity of a lunasin-enriched soybean extract (LES). The protein profile of LES was characterized, and its behavior under simulated gastrointestinal digestion was evaluated. Besides its in vitro radical scavenging capacity, LES and lunasin’s effects on cell viability, phagocytic capacity, oxidative stress, and inflammation-associated biomarkers were investigated in both RAW264.7 macrophages and lymphocytes EL4. Lunasin and other soluble peptides enriched after aqueous solvent extraction partially resisted the action of digestive enzymes, being potentially responsible for the beneficial effects of LES. This extract scavenged radicals, reduced reactive oxygen species (ROS) and exerted immunostimulatory effects, increasing nitric oxide (NO) production, phagocytic activity, and cytokine release in macrophages. Lunasin and LES also exerted dose-dependent immunomodulatory effects on EL4 cell proliferation and cytokine production. The modulatory effects of soybean peptides on both immune cell models suggest their potential protective role against oxidative stress, inflammation, and immune response-associated disorders.

Contribution of Proteins and Peptides to the Impact of a Soy Protein Isolate on Oxidative Stress and Inflammation-Associated Biomarkers in an Innate Immune Cell Model

“…This indicates that a slight enrichment of this peptide was achieved with aqueous solvent extraction. These values were in the range (9.2 to 25.7 mg of lunasin/g of protein) reported for different commercial lunasin-enriched products [36] and were slightly higher than the value recently determined in our laboratory in an albumin-enriched extract [21]. From the starting concentration of 19.45 mg of lunasin/g of protein in LPI, the final LPI-UF2 with a lunasin concentration of 58.2 mg of lunasin/g of protein presented a three-fold enrichment of this peptide.…”

“…This value was higher than that determined in untreated LPS-challenged cells (29.29 µM). Although lunasin was demonstrated to reduce the NO production induced by LPS in macrophages [ 51 ], our previous study also reported NO-inducing effects in this cell model [ 21 ].…”

“…Different properties have been attributed to lunasin such as antioxidant, anti-inflammatory, and hypocholesterolemic properties, among others [ 20 ]. In our previous study, lunasin was identified as one of the major peptides responsible for the effects of an albumin-enriched extract on different immune cell models [ 21 ]. However, in addition to lunasin, other peptides present in soybean have been reported to exert multiple health benefits such as anti-diabetic, angiotensin converting enzyme inhibitory, anti-hypertensive, phagocytosis-stimulatory, triglyceride-reducing, immunostimulatory, appetite-suppressing, proteinase-inhibitory, and chemopreventive properties, and contribute on the beneficial health attributed to this legume [ 22 ].…”

Bioactive peptides: an alternative therapeutic approach for cancer management

“…This suggests that soybean peptides, such as Lunasin and LES, have the remarkable ability to modulate or regulate both the innate and adaptive arms of the immune system. In essence, they possess the potential to modulate immune responses in different conditions ( 122 ).…”

Fine-tuning of mononuclear phagocytes for improved inflammatory responses: role of soybean-derived immunomodulatory compounds

“…Recent findings revealed that hydrolyzed soy protein containing bioactive lunasin, a 43-amino acid peptide, inhibited LPS-induced secretion of M1-type mediators (IL-1β, IL-6, and NO) through suppressing NF-κB nuclear translocation in RAW264.7 cells (44). Contrary, lunasin enhances phagocytosis and induces the production of M1-type mediators in unstimulated RAW264.7 cells, contributing to the activation of immune responses (45,46) (Table 1). Lunasin also exerts diverse effects on human monocyte-derived DCs, influencing their maturation, M1-type cytokine production, and antigen presentation, which potentiate adaptive immune responses as an adjuvant (47).…”