Food derived bioactive peptides and intestinal barrier function

Bioactive Peptides Derived from Seaweed Protein and Their Health Benefits: Antihypertensive, Antioxidant, and Antidiabetic Properties

Cardiovascular diseases and diabetes are the biggest causes of death globally. Therefore, prevention of these diseases is a focus of pharmaceuticals and functional food manufacturers. This review summarizes recent research trends and scientific knowledge in seaweed protein-derived peptides with particular emphasis on production, isolation and potential health impacts in prevention of hypertension, diabetes and oxidative stress. The current status and future prospects of bioactive peptides are also discussed. Bioactive peptides have strong potential for use in therapeutic drug and functional food formulation in health management strategy, especially cardiovascular disease and diabetes. Seaweeds can be used as sustainable protein sources in the production of these peptide-based drugs and functional foods for preventing such diseases. Many studies have reported that peptides showing angiotensin converting enzyme inhibition, antihypertensive, antioxidative and antidiabetics activities, have been successfully isolated from seaweed. However, further research is needed in large-scale production of these peptides, efficient isolation methods, interactions with functional foods and other pharmaceuticals, and their ease to digestion in in vivo studies and safety to validate the health benefits of these peptides.

Protective effects of brain-gut peptides against intestinal barrier injury and mechanisms involved

Brain-gut peptides, a group of small molecule polypeptides, have been found to distribute widely in the brain and the gastrointestinal system and act as both neurotransmitters and hormones. Intestinal barrier injury has a serious impact on the prognosis of critical diseases. Brain-gut peptides can modulate tight junction proteins, promote epithelial cell proliferation, and inhibit apoptosis and inflammatory cytokines, thus playing an important role in the maintenance of intestinal barrier and mucosal immunity. In this review, we discuss the protective effects of brain-gut peptides against intestinal barrier injury and the underlying mechanisms.

Bovine Hemoglobin Derived Peptide Asn-Phe-Gly-Lys Inhibits Pancreatic Cancer Cells Metastasis by Targeting Secreted Hsp90α

Pancreatic cancer is a digestive system malignant carcinoma with poor prognosis. The majority of patients are diagnosed with metastatic disease, which is also the leading cause of pancreatic cancer death. The aim of this study was to investigate the antimetastatic effect of Asn-Phe-Gly-Lys (NFGK), a tetrapeptide derived from bovine hemoglobin pepsin hydrolysate, on human pancreatic cancer cell line MIAPaCa-2. Wound healing assay and transwell invasion assay results showed that NFGK inhibited MIAPaCa-2 cell migration and invasion dose-dependently. Cell proliferation assay data showed that NFGK had slight cytotoxicity on MIAPaCa-2 cells. Fluorescence confocal imaging data revealed that NFGK targeted the cell membrane of MIAPaCa-2. Molecular docking data displayed that NFGK bond to the N-terminus ATP-binding pocket of secreted heat shock protein 90α (Hsp90α). Western blotting results further proved that NFGK inhibited secreted Hsp90α and downstream matrix metalloproteinase-9 (MMP-9) level dose dependently, while it did not inhibit intracellular Hsp90 and cyclin-dependent-kinase 4 (CDK4). All above results demonstrated that bovine hemoglobin derived peptide NFGK inhibited pancreatic cancer cell metastasis by targeting secreted Hsp90α and its downstream MMP-9.

PRACTICAL APPLICATION

Peptide NFGK comes from bovine hemoglobin, which is digested by pepsin in stomach after eating. After digesting to NFGK, bovine hemoglobin will obtain new function of inhibiting pancreatic cancer cell metastasis without dramatic cell toxicity. These means NFGK may help those patients who are suffering pancreatic cancer to avoid cancer cell metastasis without too much side effect.

Immunomodulating peptides for food allergy prevention and treatment

Among the most promising strategies currently assayed against IgE-mediated allergic diseases stands the possibility of using immunomodulating peptides to induce oral tolerance toward offending food allergens or even to prevent allergic sensitization. This review focuses on the beneficial effects of food derived immunomodulating peptides on food allergy, which can be directly exerted in the intestinal tract or once being absorbed through the intestinal epithelial barrier to interact with immune cells. Food peptides influence intestinal homeostasis by maintaining and reinforcing barrier function or affecting intestinal cell-signalling to nearby immune cells and mucus secretion. In addition, they can stimulate cells of the innate and adaptive immune system while supressing inflammatory responses. Peptides represent an attractive alternative to whole allergens to enhance the safety and efficacy of immunotherapy treatments. The conclusions drawn from curative and preventive experiments in murine models are promising, although there is a need for more pre-clinical studies to further explore the immunomodulating strategy and its mechanisms and for a deeper knowledge of the peptide sequence and structural requirements that determine the immunoregulatory function.

Should Research on the Nutritional Potential and Health Benefits of Fermented Cereals Focus More on the General Health Status of Populations in Developing Countries?

Cereal foods fermented by lactic acid bacteria are staples in many countries around the world particularly in developing countries, but some aspects of the nutritional and health benefits of traditional fermented foods in developing countries have not been sufficiently investigated compared to fermented foods in high-income countries. Today, malnutrition worldwide is characterized by a double burden, excess leading to non-communicable diseases like obesity or diabetes alongside micronutrient deficiencies. In addition, populations in developing countries suffer from infectious and parasitic diseases that can jeopardize the health benefits provided by their traditional fermented foods. Using examples, we argue that research on traditional fermented cereals in developing countries should focus more on their effect on inflammation and oxidative stress under conditions including infectious or non-infectious gut inflammation.

Collagen peptides ameliorate intestinal epithelial barrier dysfunction in immunostimulatory Caco-2 cell monolayers via enhancing tight junctions

Dysfunction of the intestinal barrier plays a key role in the pathogenesis of inflammatory bowel disease (IBD) and multiple organ failure. The effect of Alaska pollock skin-derived collagen and its 3 tryptic hydrolytic fractions, HCP (6 kDa retentate), MCP (3 kDa retentate) and LCP (3 kDa permeate) on TNF-α induced barrier dysfunction was investigated in Caco-2 cell monolayers. TNF-α induced barrier dysfunction was significantly attenuated by the collagen and its peptide fractions, especially LCP, compared to TNF-α treated controls (P < 0.05). Compared to a negative control, 24 h pre-incubation with 2 mg mL^-1 LCP significantly alleviated the TNF-α induced breakdown of the tight junction protein ZO-1 and occludin and inhibited MLC phosphorylation and MLCK expression. The activation of NFκB and Elk-1 was suppressed by LCP. Thus, collagen peptides may attenuate TNF-α induced barrier dysfunction of Caco-2 cells by inhibiting the NFκB and ERK1/2-mediated MLCK pathway with associated decreases in ZO-1 and occludin protein expression.

Potential role of nutraceutical compounds in inflammatory bowel disease

Conventional therapies for inflammatory bowel diseases (IBD) involve combinations of pharmacologic agents such as aminosalicylates, azathioprine, and corticosteroids. Recently, the therapeutic scenario has been heavily increased by the introduction of agents including monoclonal antibodies targeted to specific proinflammatory cytokines, to adhesion molecules, and the induction of anti-inflammatory cytokines and T-cell activation. However, the use of these drugs is accompanied by a certain number of side effects, with some of them being quite severe, rising concerns about the safety profile. Furthermore, the cost of these emerging therapeutic strategies is significant , considering the increasing incidence and the chronic trend of IBD. Nutraceuticals is a broad term used to describe any product derived from food sources claiming extra health benefits beyond the intrinsic nutritional value found in foods. The beneficial effects of nutraceutical compounds in human health have been emerging in the last decades. Although few clinical trials have been performed in IBD patients, nutraceuticals, such as herbal products or vitamins, are generally accepted as safer alternative/supplementation to conventional therapy. In vitro and IBD-animal models studies have shown their involvement in several biological processes, including antioxidant defenses, cell proliferation, gene expression, which could account for a role in the maintenance of the mucosal barrier integrity, the control of the inflammatory pathways and the modulation of the immune response. These data suggest a wide spectrum of positive effects exerted by nutraceuticals, with a high potential for a therapeutic use in humans. In the present review, the beneficial effects of the most investigated nutraceutical compounds in the setting of human IBD are discussed.

Protein hydrolysates in animal nutrition: Industrial production, bioactive peptides, and functional significance

Recent years have witnessed growing interest in the role of peptides in animal nutrition. Chemical, enzymatic, or microbial hydrolysis of proteins in animal by-products or plant-source feedstuffs before feeding is an attractive means of generating high-quality small or large peptides that have both nutritional and physiological or regulatory functions in livestock, poultry and fish. These peptides may also be formed from ingested proteins in the gastrointestinal tract, but the types of resultant peptides can vary greatly with the physiological conditions of the animals and the composition of the diets. In the small intestine, large peptides are hydrolyzed to small peptides, which are absorbed into enterocytes faster than free amino acids (AAs) to provide a more balanced pattern of AAs in the blood circulation. Some peptides of plant or animal sources also have antimicrobial, antioxidant, antihypertensive, and immunomodulatory activities. Those peptides which confer biological functions beyond their nutritional value are called bioactive peptides. They are usually 2-20 AA residues in length but may consist of >20 AA residues. Inclusion of some (e.g. 2-8%) animal-protein hydrolysates (e.g., porcine intestine, porcine mucosa, salmon viscera, or poultry tissue hydrolysates) or soybean protein hydrolysates in practical corn- and soybean meal-based diets can ensure desirable rates of growth performance and feed efficiency in weanling pigs, young calves, post-hatching poultry, and fish. Thus, protein hydrolysates hold promise in optimizing the nutrition of domestic and companion animals, as well as their health (particularly gut health) and well-being.

The Anti-Inflammatory Effect of Spray-Dried Plasma Is Mediated by a Reduction in Mucosal Lymphocyte Activation and Infiltration in a Mouse Model of Intestinal Inflammation

Spray-dried preparations from porcine and bovine plasma can alleviate mucosal inflammation in experimental models and improve symptoms in patients with enteropathy. In rodents, dietary supplementation with porcine spray-dried plasma (SDP) attenuates intestinal inflammation and improves the epithelial barrier function during intestinal inflammation induced by Staphylococcus aureus enterotoxin B (SEB). The aim of this study was to discern the molecular mechanisms involved in the anti-inflammatory effects of SDP. Male C57BL/6 mice were fed with 8% SDP or control diet (based on milk proteins) for two weeks, from weaning until day 33. On day 32, the mice were given a SEB dose (i.p., 25 µg/mouse) or vehicle. SEB administration increased cell recruitment to mesenteric lymph nodes and the percentage of activated Th lymphocytes and SDP prevented these effects). SDP supplementation increased the expression of interleukin 10 (IL-10) or transforming growth factor- β (TGF-β) compared to the SEB group. The SEB challenge increased six-fold the expression of mucosal addressin cell adhesion molecule 1 (MAdCAM-1) and intercellular adhesion molecule 1 (ICAM-1); and these effects were attenuated by SDP supplementation. SEB also augmented NF-κB phosphorylation, an effect that was prevented by dietary SDP. Our results indicate that the anti-inflammatory effects of SDP involve the regulation of transcription factors and adhesion molecules that reduce intestinal cell infiltration and the degree of the inflammatory response.

Extruded whole grain diets based on brown, soaked and germinated rice. Effects on cecum health, calcium absorption and bone parameters of growing Wistar rats. Part I

The influence of diets with whole rice processed ingredients on cecum health, calcium absorption and bone parameters was studied using an animal model.

Rice protein hydrolysates (RPHs) inhibit the LPS-stimulated inflammatory response and phagocytosis in RAW264.7 macrophages by regulating the NF-κB signaling pathway

Different RPH components inhibit LPS-induced NO and TNF-α production. RPHs-C-7-3 inhibits the expression of pro-inflammatory expression. RPHs-C-7-3 suppresses the LPS-stimulated phagocytic ability. RPHs-C-7-3 regulates the nuclear translocation of p65.

Clinical application of probiotics in type 2 diabetes mellitus: A randomized, double-blind, placebo-controlled study

BACKGROUND & AIMS

Type 2 diabetes has been associated with dysbiosis and one of the possible routes to restore a healthy gut microbiota is by the regular ingestion of probiotics. We aimed to investigate the effects of probiotics on glycemic control, lipid profile, inflammation, oxidative stress and short chain fatty acids in T2D.

METHODS

In a double-blind, randomized, placebo-controlled trial, 50 volunteers consumed daily 120 g/d of fermented milk for 6 wk. Participants were assigned into two groups: probiotic group, consuming fermented milk containing Lactobacillus acidophilus La-5 and Bifidobacterium animalis subsp lactis BB-12 (10⁹ colony-forming units/d, each) and control group, consuming conventional fermented milk. Anthropometric measurements, body composition, fasting blood and faecal samples were taken at baseline and after 6 wk.

RESULTS

45 subjects out of 50 (90%) completed follow-up. After 6 wk, there was a significant decrease in fructosamine levels (-9.91 mmol/L; p = 0.04) and hemoglobin A₁c tended to be lower (-0.67%; p=0.06) in probiotic group. TNF-α and resistin were significantly reduced in probiotic and control groups (-1.5 and -1.3 pg/mL, -.1 and -2.8 ng/mL, respectively), while IL-10 was significantly reduced (- 0.65 pg/mL; p <0.001) only in the control group. Fecal acetic acid was increased in both groups (0.58 and 0.59% in probiotic and control groups, respectively; p <0.01). There was a significant difference between groups concerning mean changes of HbA_1c (+0.31 for control group vs -0.65 for probiotic group; p=0.02), total cholesterol (+0.55 for control group vs -0.15 for probiotic group; p=0.04) and LDL-cholesterol (+0.36 for control group vs -0.20 for probiotic group p=0.03).

CONCLUSIONS

Probiotic consumption improved the glycemic control in T2D subjects, however, the intake of fermented milk seems to be involved with others metabolic changes, such as decrease in inflammatory cytokines (TNF-α and resistin) and increase in the acetic acid.

Optimization of Caco-2 and HT29 co-culture in vitro cell models for permeability studies

The purpose of this study was to investigate the appropriate proportion of Caco-2 and HT29 co-culture in vitro cell models for permeability studies. The results showed that the transepithelial electrical resistance values of 9:1 and 1:0 groups (263 ± 3.61 and 300 ± 7.55) after 21-day culture were >250 Ω cm(2), which were suitable for further experiments. The confocal laser microscopy showed that the group of 9:1 (Caco-2:HT29) had the highest integrity, whereas the group of 0:1 (Caco-2:HT29) exhibited the lowest. The staining study confirmed that mucus was successfully produced by HT29 cells, and it was also produced in co-cultures with Caco-2 cells model, but the Caco-2 monocultures did not have any blue staining, which made us affirm that mucus is only produced in the presence of HT29 cells. The real-time PCR results showed that the total highest expression level of ALPi and MUC5AC was the ratio of 9:1 (Caco-2:HT29) and lowest is 1:1 (Caco-2:HT29). So we concluded that 9:1 (Caco-2:HT29) is the optimal Caco-2 to HT29 ratio in the in vitro model co-culture for permeability studies.

Proteins and Carbohydrates from Red Seaweeds: Evidence for Beneficial Effects on Gut Function and Microbiota

Based on their composition, marine algae, and namely red seaweeds, are good potential functional foods. Intestinal mucosal barrier function refers to the capacity of the intestine to provide adequate containment of luminal microorganisms and molecules. Here, we will first outline the component of seaweeds and will summarize the effects of these on the regulation of mucosal barrier function. Special attention will be paid to unique components of red seaweeds: proteins and derived peptides (e.g., phycobiliproteins, glycoproteins that contain “cellulose binding domains”, phycolectins and the related mycosporine-like amino acids) together with polysaccharides (e.g., floridean starch and sulfated galactans, such as carrageenans, agarans and “dl-hybrid”) and minerals. These compounds have been shown to exert prebiotic effects, to regulate intestinal epithelial cell, macrophage and lymphocyte proliferation and differentiation and to modulate the immune response. Molecular mechanisms of action of peptides and polysaccharides are starting to be elucidated, and evidence indicating the involvement of epidermal growth factor receptor (EGFR), insulin-like growth factor receptor (IGFR), Toll-like receptors (TLR) and signal transduction pathways mediated by protein kinase B (PKB or AKT), nuclear factor-κB (NF-κB) and mitogen activated protein kinases (MAPK) will also be summarized. The need for further research is clear, but in vivo experiments point to an overall antiinflammatory effect of these algae, indicating that they can reinforce membrane barrier function.

Intestinal flora and irritable bowel syndrome

Irritable bowel syndrome (IBS) is one of the most common gastrointestinal disorders. The pathogenesis of IBS is not fully clear up to now, but numerous studies suggest that it is related to multiple factors, such as abnormal intestinal motility, visceral hypersensitivity, intestinal infection and immunoreaction, and imbalanced intestinal microbiota. The dysbiosis of the gastrointestinal tract microbiota is considered one of the most important factors responsible for the development of IBS. In this article, we will discuss the relationship between intestinal microbiota and IBS.