Pepsin-pancreatin hydrolysis reduced the ability of lunasin-enriched material to inhibit activation of the inflammasomes in THP-1 human macrophages

Food-derived peptides as novel therapeutic strategies for NLRP3 inflammasome-related diseases: a systematic review

NLRP3 (NOD-, LRR- and pyrin domain-containing protein 3), a member of the nucleotide-binding domain (NOD) and leucine-rich repeat sequence (LRR) protein (NLR) family, plays an essential role in the inflammation initiation and inflammatory mediator secretion, and thus is also associated with many disease progressions. Food-derived bioactive peptides (FDBP) exhibit excellent anti-inflammatory activity in both in vivo and in vitro models. They are encrypted in plant, meat, and milk proteins and can be released under enzymatic hydrolysis or fermentation conditions, thereby hindering the progression of hyperuricemia, inflammatory bowel disease, chronic liver disease, neurological disorders, lung injury and periodontitis by inactivating the NLRP3. However, there is a lack of systematic review around FDBP, NLRP3, and NLRP3-related diseases. Therefore, this review summarized FDBP that exert inhibiting effects on NLRP3 inflammasome from different protein sources and detailed their preparation and purification methods. Additionally, this paper also compiled the possible inhibitory mechanisms of FDBP on NLRP3 inflammasomes and its regulatory role in NLRP3 inflammasome-related diseases. Finally, the progress of cutting-edge technologies, including nanoparticle, computer-aided screening strategy and recombinant DNA technology, in the acquisition or encapsulation of NLRP3 inhibitory FDBP was discussed. This review provides a scientific basis for understanding the anti-inflammatory mechanism of FDBP through the regulation of the NLRP3 inflammasome and also provides guidance for the development of therapeutic adjuvants or functional foods enriched with these FDBP.

Lunasin reduces the susceptibility of IL-10 deficient mice to inflammatory bowel disease and modulates the activation of the NLRP3 inflammasome

Inflammatory bowel disease (IBD) is a chronic inflammatory condition that can cause severe damage to the gastrointestinal tract leading to lower quality of life and productivity. Our goal was to investigate the protective effect of the soy peptide lunasin in an in vivo model of susceptibility to IBD and to identify the potential mechanism of action in vitro. In IL-10 deficient mice, oral administration of lunasin reduced the number and frequency of mice exhibiting macroscopic signs of susceptibility to inflammation and significantly decreased levels of the pro-inflammatory cytokines TNF-α, IL-1β, IL-6, and IL-18 by up to 95%, 90%, 90%, and 47%, respectively, in different sections of the small and large intestines. Dose-dependent decrease of caspase-1, IL-1β, and IL-18 in LPS-primed and ATP-activated THP-1 human macrophages demonstrated the ability of lunasin to modulate the NLRP3 inflammasome. We demonstrated that lunasin can decrease susceptibility to IBD in genetically susceptible mice by exerting anti-inflammatory properties.

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

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.

Extraction and immunomodulatory activity of the polysaccharide obtained from Craterellus cornucopioides

In this study, we investigated the structural features of the polysaccharide obtained from Craterellus cornucopioides (CCP2) by high-performance liquid chromatography, Fourier transform infrared spectroscopy and ion chromatography. The results showed that CCP2 was a catenarian pyranose that principally comprised of mannose, galactose, glucose, and xylose in the ratio of 1.86: 1.57: 1.00: 1.14, with a molecular weight of 8.28 × 10⁴ Da. Moreover, the immunoregulation effect of CCP2 was evaluated both in vitro and in vivo. It displayed a remarkable immunological activity and activation in RAW264.7 cells by enhancing the phagocytosis of macrophages in a dose-dependent manner without showing cytotoxicity at the concentrations of 10–200 μg/mL in vitro. Additionally, Histopathological analysis indicated the protective function of CCP2 against immunosuppression induced by cyclophosphamide (Cy). Meanwhile, the intake of CCP2 had better immunoregulatory activity for immunosuppression BALB/c mice model. After prevention by CCP2, the spleen and thymus weight indexes of BALB/c mice model were significantly increased. The RT-qPCR and Western Blot results provided comprehensive evidence that the CCP2 could activate macrophages by enhancing the production of cytokines (IL-2, IL-6, and IL-8) and upregulating the protein expression of cell membrane receptor TLR4 and its downstream protein kinase (TRAF6, TRIF, and NF-κB p65) production of immunosuppressive mice through TLR4-NFκB p65 pathway. The results demonstrated that CCP2 could be a potential prebiotic and might provide meaningful information for further research on the immune mechanism.

Lunasin Peptide is a Modulator of the Immune Response in the Human Gastrointestinal Tract

INTRODUCTION

Lunasin is a soybean bioactive peptide with a variety of beneficial properties against chronic disorders. However, its effect in human primary intestinal cells remains unknown. Hence, this study aims to characterize its ex vivo biological activity in the human intestinal mucosa.

METHODS AND RESULTS

Human intestinal biopsies, obtained from healthy controls, are ex vivo conditioned with lunasin both in the presence/absence of lipopolysaccharide (LPS). Peptide maintains its stability during biopsy culture by HPLC-MS/MS analysis. Lunasin is bioactive in the human mucosa, as it induces IL-1β, TNF-α, IL-17A, CCL2, and PGE2/COX-2 gene expression together with an increased expression of tolerogenic IL-10 and TGFβ, while it also downregulates the expression of iNOS and subunit p65 from NF-κB. Indeed, lunasin also abrogates the LPS-induced pro-inflammatory response, downregulating IL-17A, IFNγ, and IL-8 expression, and inducing IL-10 and TGFβ expression. These results are also mirrored in the cell-free culture supernatants at the protein level by Multiplex. Moreover, lunasin further induces a regulatory phenotype and function on human intestinal conventional dendritic cell and macrophage subsets as assessed by flow cytometry.

CONCLUSIONS

We hereby have characterized lunasin as an immunomodulatory peptide with potential capacity to prevent immune and inflammatory-mediated disorders in the human gastrointestinal tract.

A Comparative Study on Phenolic Content, Antioxidant Activity and Anti-Inflammatory Capacity of Aqueous and Ethanolic Extracts of Sorghum in Lipopolysaccharide-Induced RAW 264.7 Macrophages

Sorghum is an important cereal with diverse phenolic compounds that have potential health promoting benefits. The current study comparatively characterized the phenolic contents of two novel black-seeded sorghum lines (SC84 and PI570481) using different extraction systems (water, ethanol and their acidified counterparts) and evaluated their antioxidant and anti-inflammatory activities. Phenolic compositions were determined by spectrophotometric assays and HPLC analysis. Antioxidant activities were assessed by radical scavenging effects on nitric oxide (NO) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals, and the oxygen radical absorbance capacity (ORAC). Anti-inflammatory capacity was estimated by measuring levels of pro-inflammatory markers produced by lipopolysaccharide (LPS)-induced RAW 264.7 macrophages. Results showed that effects of solvent types and HCl on extraction efficiency differed among phenolic compounds and sorghum samples. Tannins were the most dominant polyphenols in the studied extracts (11.11-136.11 mg epicatechin equivalent/g sorghum). Sorghum extracts exerted more potent scavenging activity on DPPH than NO radicals. In LPS-activated RAW264.7 cells, sorghum extracts dose-dependently inhibited the production of NO, interleukin-6 (IL-6), and intracellular reactive oxygen species (ROS), with ethanolic extracts showing greater anti-inflammatory activity. Positive correlations were noted between tannin content and DPPH radical scavenging activity, and anti-inflammatory capacity. These results suggest the potential role of tannin-rich sorghum extracts against inflammation and associated diseases.

Research on the structural characteristics of a novel Chinese Iron Yam polysaccharide and its gastroprotection mechanism against ethanol-induced gastric mucosal lesion in a BALB/c mouse model

In this study, a triple-helix Chinese Iron Yam polysaccharide (CIYP) with a molecular weight of 1.67 × 10³ kDa was obtained. The CIYP was extracted with deionized water followed by deproteination, decoloration and purification using anion-exchange chromatography and size exclusion chromatography. Its structural characteristics and micromorphology were investigated by GC-MS, periodate oxidation and Smith degradation, FT-IR, NMR spectroscopy, SEM and AFM. The results showed that CIYP is a catenarian polysaccharide composed of rhamnose, arabinose, mannose, glucose, galactose and galacturonic acid in the ratio of 1 : 1.33 : 8.31 : 2.83 : 1.12 : 2.62. Meanwhile, the gastric mucosa protective effect of CIYP on an ethanol-injured BALB/c mouse model was investigated. It was found that the preventive CIYP-treatment groups (200 and 400 mg kg^-1 d^-1) showed gastric mucosa protective effects on the BALB/c mouse model. The lesion index and lesion inhibition rate of the CIYP and cimetidine treatment groups were significantly altered compared with the ethanol-induced gastric mucosal lesion (GML) group. Moreover, the administration of CIYP showed definite effects of increasing the NO, PGE2 and EGF levels, and SOD activities, and reducing the MDA levels of gastric mucosa tissues to prevent gastric oxidative stress. Histopathological analysis indicated that the microscopic morphology of gastric mucosal tissues was changed after being damaged by ethanol and the damage was significantly reduced after CIYP administration. Finally, the western blot and quantitative real-time polymerase chain reaction (qRT-PCR) results provided comprehensive evidence that the CIYP could repress gastric inflammation through the reduction of IL-1β, TNF-α and IL-6, prevent gastric oxidative stress through the inhibition of lipid peroxides, and favor cell survival via downregulating the TAK1, MKK3, P-p38 and Bax levels and upregulating the protein expression levels, compared with the CIM group.

Lunasin abrogates the expression of matrix metalloproteinases and reduction of type II collagen

Impairment of type II collagen caused by MMPs in response to overproduction of IL-1β is an important step in the pathological progression of osteoarthritis (OA). Lunasin, a well-known peptide present in the soybean, has displayed a positive impact on numerous physiological functions. Little information in the effects of lunasin on cartilage degradation has been sought in clinical research before. Here, we report that lunasin suppressed the increase in MMP-3 and MMP-13 caused by IL-1β. In addition, we found that lunasin could prevent the decrease in TIMP-1 and TIMP-2 expressions caused by IL-1β. Notably, lunasin suppressed reduction of type II collagen, the basis for articular cartilage. Lunasin also attenuated activation of the JAK2/STAT1/IRF-1 pathway. These effects of lunasin suggest that it might become a promising therapeutic agent for chondro-protective therapy.

Sorghum Phenolics Inhibits Inflammasomes in Lipopolysaccharide (LPS)-Primed and Adenosine Triphosphate (ATP)-Activated Macrophages

Sorghum contains phenolic compounds with reported biological activities. The objective was to evaluate the ability of sorghum phenolic extract to inhibit inflammasomes in THP-1 human macrophages. THP-1 human macrophages was pre-treated with sorghum phenolics and the inflammasome was activated by lipopolysaccharide and adenosine triphosphate treatment. Treatment of macrophages with 50 μg sorghum extract/mL reduced IL-1β and IL-18 secretion by 59.7 and 32.0%, respectively, associated with caspase-1 activity reduction. Moreover, the production of intracellular reactive oxygen species was reduced. Our data showed the potential role of sorghum phenolics in diseases associated with aberrant inflammasomes activation.

A novel polysaccharide obtained from Craterellus cornucopioides enhances immunomodulatory activity in immunosuppressive mice models via regulation of the TLR4-NF-κB pathway

The immunoregulatory effect of a novel Craterellus cornucopioides polysaccharide (CCP) with a triple-helix structure on immunosuppressive BALB/c mice models was investigated; moreover, the immune response of BALB/c mice models in the preventive and therapeutic treatment groups treated with CCP was explored, and its molecular mechanism was elucidated. It was found that the BALB/c mice models in the preventive groups treated with CCP (120 and 240 mg kg^-1 d^-1) had better immunoregulatory activity. The spleen and thymus weight indices of the BALB/c mice models were significantly increased, and the histopathological analysis indicated a protective function of CCP against the immunosuppression induced by cyclophosphamide (CTX). Moreover, CCP displayed definite and clear synergistic effects on the T- or B-lymphocyte proliferation induced by ConA or LPS, respectively, promoted the natural killer (NK) cell activity and significantly increased phagocytic activity to activate peritoneal macrophages in immunosuppressive mice. The western blot and quantitative real-time polymerase chain reaction (qRT-PCR) results provided comprehensive evidence that CCP could upregulate the protein expression of the G-protein-coupled cell membrane receptor TLR4 and the production of its downstream protein kinases (TRAF6, TK1, p-IKKα/β and NF-κB p50); this, in turn, enhanced the production of cytokines (IL-2, IL-6, TNF-α and IFN-α) through both preventive and therapeutic treatments via regulation of the TLR4-NFκB pathway in the peritoneal macrophage of immunosuppressive mice.

Elucidation of The Anti-Inflammatory Effect of Vanillin In Lps-Activated THP-1 Cells

Vanillin, a kind of phenolic compound, is naturally found in food and beverage and widely used as a flavoring agent. In view of the safety and universality of vanillin, exploring the functions of vanillin on human is of great value. Thus, lipopolysaccharide (LPS)-activated THP-1 cells were selected as the cell model to evaluate the anti-inflammatory effect of vanillin in this study. On the basis of the results, vanillin markedly suppressed the expression of inflammatory cytokines (that is, TNF-α, IL-1β, IL-6, and IL-8), mediators (NO, iNOS, PGE2, and COX-2), and NLRP3 inflammasome (that is, NLRP3, ASC, and caspase-1), blocked the LPS-induced activation of the NF-κB/IκBα/AP-1 signaling pathway, and activated the gene expression of the Nrf2/HO-1 signaling pathway. In addition, it was confirmed that vanillin was unable to react with LPS due to the results of quantification by HS-SPME-GC-MS. Hence, vanillin could effectively attenuate LPS-induced inflammatory response by regulating the expression of intracellular signaling pathways in THP-1 cells. It is a potent anti-inflammatory component found in food and beverage. These findings might contribute to the overall understanding of the potential health benefits of vanillin for food application. PRACTICAL APPLICATION: In this study, the anti-inflammatory effect of vanillin (VA) was evaluated by ELISA, real-time PCR, and western blot in LPS-induced THP-1 cells. The hypothesis that VA could react with LPS was excluded due to the results of quantification by HS-SPME-GC-MS. On the basis of the result, vanillin could effectively attenuate LPS-induced inflammatory response in THP-1 cells and was a potent anti-inflammatory component natural in food and beverage. These findings might contribute to the overall understanding of the potential health benefits of vanillin for food application.

Current state of art after twenty years of the discovery of bioactive peptide lunasin

Non-communicable diseases have become the medical challenge of the 21st century because of their high incidence and mortality rates. Accumulating evidence has suggested that the modulation of diet and other lifestyle habits is the best strategy for the prevention of these diseases. An increasing number of dietary compounds have been found to exert health promoting benefits beyond their nutritional effects. Among them, lunasin is considered one of the most studied bioactive peptides. Since its discovery in soybean twenty years ago, many researchers around the world have focused their studies on demonstrating the chemopreventive and chemotherapeutic activity of lunasin. Moreover, in the last years, promising protective effects of this peptide against hypercholesterolemia, obesity, metabolic syndrome and associated cardiovascular disorders, and inflammatory and immune-regulated diseases have been described. This review summarizes recent remarkable advances on the use of peptide lunasin as a potential functional ingredient to provide health benefits. Moreover, novel aspects related to the influence of lunasin's digestion and bioavailability, the mechanisms of action proposed to explain the underlying biological properties, and the incorporation of this peptide into nutritional supplements are critically discussed.

Anti-inflammatory Mechanism Involved in 4-Ethylguaiacol-Mediated Inhibition of LPS-Induced Inflammation in THP-1 Cells

4-Ethylguaiacol, a common aroma compound of baijiu (a traditional Chinese alcoholic beverage), was assessed for its potential anti-inflammatory effects in an LPS-induced THP-1 cell model. To characterize the effect of 4-ethylguaiacol on the LPS-induced inflammatory response, the mRNA and protein expression of the TLR4-MAPKs-NF-κB-IκBα-AP-1, Nrf2-HO-1, and AMPK-SIRT1 pathways were monitored by ELISA, real-time PCR, and Western blotting. On the basis of the result, 4-ethylguaiacol exerted anti-inflammatory effects at doses of 10, 100, and 500 μM (the concentration of 4-ethylguaiacol in gujinggong baijiu is in the range of 1044 ± 44 to 1661 ± 63 μg/L) and significantly mitigated LPS-induced inflammation via activation of the Nrf2-HO-1 and AMPK-SIRT1 pathways and inhibition of NF-κB and AP-1 activation, thereby markedly inhibiting the activation of inflammasomes and down-regulating the production of inflammatory cytokines. These results indicated that 4-ethylguaiacol could reverse LPS-induced inflammatory responses and is a natural, potent anti-inflammatory component in baijiu.

Kafirin from Sorghum bicolor inhibition of inflammation in THP-1 human macrophages is associated with reduction of intracellular reactive oxygen species

Aberrant inflammation as a result of activation of the transmembrane protein Toll-like receptor 4 belonging to pattern recognition receptor and subsequent phosphorylation of signaling proteins facilitated by reactive oxygen species has been linked to a myriad of diseases. Sorghum is a drought-resistant cereal with health promoting properties associated with its biologically active substances such as kafirin. Kafirin is an alcohol soluble protein and accounts for as much as 70% of the total proteins in sorghum. The objective was to determine the effect of kafirin on lipopolysaccharide (LPS)-induced inflammation in THP-1 human macrophages. THP-1 human monocytic leukemia cells were differentiated into macrophages by phorbol-12-myristate 13-acetate followed by treatment of LPS with or without 50 μg/mL or 100 μg/mL concentrations of kafirin. Kafirin at 100 μg/mL reduced the production of pro-inflammatory cytokines IL-1β, IL-6 and TNF-α by 28.3%, 74.0%, and 81.4%, respectively. Kafirin reduced production of intracellular reactive oxygen species is associated with reduced phosphorylation of extracellular regulated kinase1/2 and c-JUN N-terminal kinase and nuclear translocation of p65 and c-JUN transcription factors. Our results showed for the first time the anti-inflammatory property of kafirin purified from sorghum in LPS-induced THP-1 human macrophages.