VF-4 and DR-8 Derived from Salted Egg White Inhibit Inflammatory Activity via NF-κB/PI3K-Akt/MAPK Signal Transduction Pathways in HT-29 Cells Induced by TNF-α

Potential Benefits of Egg White Proteins and Their Derived Peptides in the Regulation of the Intestinal Barrier and Gut Microbiota: A Comprehensive Review

Impaired intestinal barrier function can impede the digestion and absorption of nutrients and cause a range of metabolic disorders, which are the main causes of intestinal disease. Evidence suggests that proper dietary protein intake can prevent and alleviate intestinal diseases. Egg white protein (EWP) has received considerable attention, because of its high protein digestibility and rich amino acid composition. Furthermore, bioactive peptides may have an increased repair effect due to their high degradation efficiency in the gut. In this study, we aimed to review the effects of EWP and its bioactive peptides on intestinal structural repair. The potential modulation mechanisms by which EWP and their peptides regulate the gut microbiota and intestinal barrier can be summarized as follows: (1) restoring the structure of the intestinal barrier to its intact form, (2) enhancing the intestinal immune system and alleviating the inflammatory response and oxidative damage, and (3) increasing the relative abundance of beneficial bacteria and metabolites. Further in-depth analysis of the coregulation of multiple signaling pathways by EWP is required, and the combined effects of these multiple mechanisms requires further evaluation in experimental models. Human trials can be considered to understand new directions for development.

Ovotransferrin Inhibits TNF-α Induced Inflammatory Response in Gastric Epithelial Cells via MAPK and NF-κB Pathway

Ovotransferrin (OVT) has been confirmed to have anti-inflammatory activity. However, its effect and mechanism on gastric inflammation are unclear. In this study, the effect and mechanism of the OVT on the tumor necrosis factor-α (TNF-α) induced inflammatory response in gastric epithelial cells (GES-1) were investigated. The enzyme linked immunosorbent assay (ELISA) was used to determine the levels of inflammation cytokines, followed by RNA sequencing to explore the potential pathways of its anti-inflammatory effect, and then it was validated by Western blotting and pathways inhibitors. Results showed that the OVT at concentrations of 50-400 μg/mL displayed nontoxicity against GES-1 cells. Additionally, 100 μg/mL of OVT obviously reduced the secretion of interleukin (IL)-8, IL-6, and TNF-α by 63.02% (630.09/1703.98), 35.53% (935.81/1451.43), and 36.19% (964.60/1511.63), respectively. The results of RNA sequencing exhibited that the OVT significantly influences the activation of mitogen-activated protein kinase (MAPK) and the nuclear factor kappa-light-chain enhancer of activated B cell (NF-κB) pathways, which was verified by the levels of p-IKK, p-IκB, p-P65, p-ERK, p-JNK, and p-P38 protein. IL-8 contents released by GES-1 cells after incubation with inhibitors of NF-κB and MAPK pathways further confirmed that OVT hindered activation of these two pathways. Collectively, these results suggested that OVT was a natural protein with the potential to treat gastric inflammation.

Ovotransferrin alleviated acute gastric mucosal injury in BALB/c mice caused by ethanol

Acute gastric mucosal injury is a common gastrointestinal disorder, which influences patients' life quality. It was found that ovotransferrin (OVT) reduces the abundance of Helicobacter pylori associated with gastric disease in the intestine of immunosuppressed mice. To clarify its gastric protective function, the present study investigated the effect of OVT on BALB/c mice with ethanol-induced gastric mucosal injury. Results showed that OVT attenuated the ethanol-induced gastric mucosal injury. Furthermore, OVT effectively downregulated the expression of inflammatory markers (tumor necrosis factor-α, interleukin (IL)-1β and IL-6) but enhanced the secretion of IL-4, IL-10 and prostaglandin E2. And OVT pretreatment significantly inhibited the activation of the MAPK/NF-κB pathway. Additionally, OVT improved gastric antioxidant ability by increasing superoxide dismutase and glutathione levels and decreasing malondialdehyde and myeloperoxidase content. Pretreatment with OVT modulated the equilibrium between B-cell lymphoma-2 (Bcl-2) and Bcl-2-associated X. The above results indicated that OVT alleviated inflammatory responses, oxidative stress and apoptosis in gastric mucosal injury mice caused by ethanol.

Production of Corn Protein Hydrolysate with Glutamine-Rich Peptides and Its Antagonistic Function in Ulcerative Colitis In Vivo

Ulcerative colitis is a typical chronic inflammatory disease of the gastrointestinal tract, which has become a serious hazard to human health. The purpose of the present study was to evaluate the antagonistic effect of corn protein hydrolysate with glutamine-rich peptides on ulcerative colitis. The sequential hydrolysis of corn gluten meal by Alcalase and Protamex was conducted to prepare the hydrolysate, and then the mouse ulcerative colitis model induced by dextran sulfate sodium was applied to evaluate its biological activities. The results indicated that the hydrolysate significantly improved weight loss (p < 0.05), reduced the colonic shortening and the disease activity index, diminished the infiltration of inflammatory cells in the colonic tissue, and reduced the permeability of the colonic mucosa in mice. In addition, the hydrolysate decreased the contents of pro-inflammatory factors IL-1β, IL-6, and TNF-α, increased the anti-inflammatory factor IL-10 and oxidative stress markers GSH-Px and SOD in the animal tests. Moreover, the hydrolysate also regulated the abundance and diversity of the intestinal microbiota, improved the microbiota structure, and increased the content of beneficial bacteria including Lactobacillus and Pediococcus. These results indicated that the hydrolysate might be used as an alternative natural product for the prevention of ulcerative colitis and could be further developed into a functional food.

Anti-inflammatory effects of tripeptide WLS on TNF-α-induced HT-29 cells and DSS-induced colitis in mice

Inflammatory bowel disease is a chronic disease of the intestinal tract, which is related to increased levels of various inflammatory mediators. This study aims to explore the anti-inflammatory mechanism of small molecular peptide WLS and its alleviating effect on inflammatory bowel disease (IBD). In TNF-α-induced HT-29 cells, WLS inhibited IL-8 secretion, decreased gene expression of pro-inflammatory cytokines IL-8, IL-6, IL-1β, and TNF-α, and inhibited the activation of MAPK/NF-κB signaling pathways. In the dextran sulfate sodium salt (DSS) induced colitis mouse model, WLS inhibited weight loss and disease activity index scores, increased colon length, improved colon histopathology, inhibited secretion of IL-6 and TNF-α in the colon, and down-regulated gene expression of pro-inflammatory cytokines (IL-6, TNF-α, IL-1β, IFN-γ, IL-17A). This study revealed that WLS was a novel small molecule peptide with anti-inflammatory activity and may be a potential candidate for the treatment of inflammatory bowel disease.