Milk‑derived hexapeptide PGPIPN prevents and attenuates acute alcoholic liver injury in mice by reducing endoplasmic reticulum stress

Bioactive peptides as a novel strategy to prevent alcoholic liver injury

Alcohol intake has become one of the leading risks to human health and wellness, among which acute and/or chronic alcohol-induced liver injury is a leading threaten, with few therapeutic options other than abstinence. In recent years, studies suggested that certain bioactive peptides from food sources could represent natural and safe alternatives for the prevention of alcoholic liver injury. Hence, this chapter focus on the advanced research on bioactive peptides exerting hepatoprotective activity against alcoholic liver injury. The main sources of protein, strategies for the preparation of hepatoprotective hydrolysates and peptides, underlying mechanisms of peptides on hepatoprotection, and possible structure-activity relationship between peptides and hepatoprotective activity were summarized and discussed, aiming to give a systematic insight into the research progress of hepatoprotective peptides. However, more efforts would be needed to give a clearer insight into the underlying mechanisms and structure-activity relationship before using hepatoprotective peptides as functional food ingredients or dietary supplements.

Tripterygium glycosides improve abnormal lipid deposition in nephrotic syndrome rat models

OBJECTIVE

The purpose of this study was to determine the effect of tripterygium glycosides (TGs) on regulating abnormal lipid deposition in nephrotic syndrome (NS) rats.

METHODS

Sprague-Dawley (SD) rats were injected with 6 mg/kg doxorubicin to construct nephrotic syndrome models (n = 6 per group), and then administered with TGs (10 mg/kg·d^-1), prednisone (6.3 mg/kg·d^-1), or pure water for 5 weeks. Biomedical indexes, such as urine protein/creatinine ratio (PCR), blood urea nitrogen (BUN), serum creatinine (Scr), serum albumin (SA), triglycerides (TG), total cholesterol (TC)were investigated to evaluate the renal injury of rats. H&E staining experiment was used to assess the pathological alterations. Oil Red O staining was used to assess the level of renal lipid deposition. Malondialdehyde (MDA) and glutathione (GSH) were measured to assess the extent of oxidative damage to the kidney. TUNEL staining was used to assess the status of apoptosis in the kidney. Western blot analysis was performed to examine the levels of relevant intracellular signaling molecules.

RESULTS

After treatment with TGs, those tested biomedical indexes were significantly improved, and the extent of kidney tissue pathological changes and lipid deposition in the kidney was diminished. Treatment with TGs decreased renal oxidative damage and apoptosis. Regarding the molecular mechanism, TGs significantly increased the protein expression levels of Bcl-2 but decreased the levels of CD36, ADFP, Bax, and Cleaved caspase-3.

CONCLUSION

TGs alleviates renal injury and lipid deposition induced by doxorubicin, suggesting that it may be a new strategy for reducing renal lipotoxicity in NS.

Bioactive milk peptides: an updated comprehensive overview and database

Partial digestion of milk proteins leads to the formation of numerous bioactive peptides. Previously, our research team thoroughly examined the decades of existing literature on milk bioactive peptides across species to construct the milk bioactive peptide database (MBPDB). Herein, we provide a comprehensive update to the data within the MBPDB and a review of the current state of research for each functional category from in vitro to animal and clinical studies, including angiotensin-converting enzyme (ACE)-inhibitory, antimicrobial, antioxidant, dipeptidyl peptidase (DPP)-IV inhibitory, opioid, anti-inflammatory, immunomodulatory, calcium absorption and bone health and anticancer activity. This information will help drive future research on the bioactivities of milk peptides.

Bifidobacterium lactis TY-S01 protects against alcoholic liver injury in mice by regulating intestinal barrier function and gut microbiota

Alcohol-induced liver injury poses a significant threat to human health. Probiotics have been proven to prevent and treat alcohol-induced liver injury. In this study, the preventive effect of Bifidobacterium lactis TY-S01 on alcohol-induced liver injury in mice was investigated. TY-S01 pretreatment effectively protected mice against alcohol-induced liver injury by preserving the levels of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, triglyceride and high-density lipoprotein-cholesterol in serum and maintaining the levels of the inflammatory cytokines tumor necrosis factor-α, interleukin-6 and interleukin-1β in liver tissue. Additionally, TY-S01 could maintain the endotoxin levels in serum, maintain the mRNA expression levels of zonula occluden-1, occludin, claudin-1 and claudin-3 in the gut, and prevent gut microbiota dysbiosis in mice with alcoholic liver injury. Spearman's correlation analysis revealed that there was a clear correlation among serum indicators, inflammatory cytokines and gut microbiota. In conclusion, TY-S01 attenuates alcohol-induced liver injury by protecting the integrity of the intestinal barrier and maintaining the balance of the gut microbiota.

Bifidobacterium lactis TY-S01 protects against alcoholic liver injury in mice by regulating intestinal barrier function and gut microbiota

Alcohol-induced liver injury poses a significant threat to human health. Probiotics have been proven to prevent and treat alcohol-induced liver injury. In this study, the preventive effect of Bifidobacterium lactis TY-S01 on alcohol-induced liver injury in mice was investigated. TY-S01 pretreatment effectively protected mice against alcohol-induced liver injury by preserving the levels of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, triglyceride and high-density lipoprotein-cholesterol in serum and maintaining the levels of the inflammatory cytokines tumor necrosis factor-α, interleukin-6 and interleukin-1β in liver tissue. Additionally, TY-S01 could maintain the endotoxin levels in serum, maintain the mRNA expression levels of zonula occluden-1, occludin, claudin-1 and claudin-3 in the gut, and prevent gut microbiota dysbiosis in mice with alcoholic liver injury. Spearman's correlation analysis revealed that there was a clear correlation among serum indicators, inflammatory cytokines and gut microbiota. In conclusion, TY-S01 attenuates alcohol-induced liver injury by protecting the integrity of the intestinal barrier and maintaining the balance of the gut microbiota.

Protective Effect of Polyphenols, Protein, Peptides, and Polysaccharides on Alcoholic Liver Disease: A Review of Research Status and Molecular Mechanisms

Alcoholic liver disease (ALD) has emerged as an important public health problem in the world. The polyphenols, protein, peptides, and polysaccharides have attracted attention for prevention or treatment of ALD. Therefore, this paper reviews the pathogenesis of ALD, the relationship between polyphenols, peptides, polysaccharides, and ALD, and expounds the mechanism of gut microbiota on protecting ALD. It is mainly found that the hydroxyl group of polyphenols endows it with antioxidation to protect ALD. The ALD protection of bioactive peptides is related to amino acid composition. The ALD protection of polysaccharides is related to the primary structure. Meanwhile, polyphenols, protein, peptides, and polysaccharides prevent or treat ALD by antioxidation, anti-inflammatory, antiapoptosis, lipid metabolism, and gut microbiota regulation. This contribution provides updated information on polyphenols, protein, peptides, and polysaccharides in response to ALD, which will not only facilitate the development of novel bioactive components but also the future application of functional food raw materials will be promoted.

A dipeptidyl peptidase IV inhibitory peptide relieves palmitic acid-induced endoplasmic reticulum stress in HepG2 cells independent of inhibiting dipeptidyl peptidase IV activity

The peptide VLATSGPG (VLA) is known to inhibit dipeptidyl peptidase IV (DPP-IV), although its mechanism in relieving endoplasmic reticulum (ER) stress is unclear. In this study, we found that treating HepG2 cells with 1.0 mM VLA reduced DPP-IV activity by 73.7 ± 4.8% without changing the DPP-IV mRNA expression level. In addition, 1.0 and 0.5 mM VLA alleviated palmitic acid (PA)-induced cell death and intracellular calcium imbalances. The levels of apoptosis-related proteins (caspase-3, caspase-9, and CHOP) were reduced by VLA treatment, which was presumed to be related to ER stress. Further studies confirmed that VLA alleviated PA-induced morphological damage to the ER and reduced the levels of the ER stress marker proteins (BIP, p-PERK, and p-IRE1α). VLA alleviated PA-induced ER stress in HepG2 cells independent of DPP-IV enzymatic activity inhibition. These findings have implications for developing novel treatment approaches for liver diseases caused by ER stress.

Role of bioactive peptides derived from food proteins in programmed cell death to treat inflammatory diseases and cancer

Bioactive peptides are specific peptide which usually contains 2-20 amino acid residues and actively exerts various functions and biological activities and ultimately affect health. Programmed cell deaths are some styles of cell death discovered in recent years, which is the key to tissue development and balance, eliminating excess, damaged or aging cells. More importantly, programmed cell death is a potential way to treat inflammatory diseases and cancer. In this review, through screening references from 2015 to present, we introduce the effect of bioactive peptides derived from food proteins on inflammatory diseases or cancer through regulating programmed cell deaths, including apoptosis, autophagy, pyroptosis, ferroptosis, and necroptosis. And this review also introduces the targets of these bioactive peptides to regulate programmed cell death. The purpose of this review is to help to expand the prospective applications of bioactive peptides in the field of inflammatory disease and cancer to provide some guidance.

Bioactive Hexapeptide Reduced the Resistance of Ovarian Cancer Cells to DDP by Affecting HSF1/HSP70 Signaling Pathway

Ovarian cancer is the leading cause of death in gynecologic malignancies. Ovarian cancer as a metastatic malignant tumor is highly recurrent and prone to drug resistance. Bioactive peptides are an emerging area of biomedical research in reducing resistance of tumor cell to drugs. In this paper, we investigated the effects and mechanisms of bioactive hexapeptide (PGPIPN) derived in milk protein on the sensitivity of ovarian cancer cells to cis-dichlorodiammine platinum (DDP). Human ovarian cancer cell lines (SKOV3 and COC1), their DDP-resistant sublines (SKOV3/DDP and COC1/DDP) and human primary ovarian cancer cells were cultured in vitro under the combined treatment of DDP (close to IC50) and different concentrations of PGPIPN. The viabilities, apoptosis and cell cycle changes were respectively measured by WST-8 and flow cytometry. The mRNA and protein expression levels of HSF1, HSP70, MDR1, ERCC1 and β-actin gene were respectively assayed by RT-qPCR and western blotting. The results showed that PGPIPN significantly increased the sensitivity of human ovarian cancer cells to DDP in inhibiting viability and inducing apoptosis in vitro. But the effects in sensitive cells were lower than DDP-resistant cells. PGPIPN significantly changed the cell cycles in all human ovarian cancer cells, which leaded to a significant increase in the percentage of cells blocked at G2/M phase and decrease the percentage of cells at G1 phases in a dose-dependent manner. PGPIPN affected the expression levels of HSF1, HSP70, MDR1 and ERCC1 genes. Compared with cells in DDP treatment alone, the expression levels of HSF1 and HSP70 in human ovarian cancer cells treated with DDP and PGPIPN together significantly decreased in dose-dependent manner. PGPIPN significantly decreased MDR1 and ERCC1 of drug-resistant ovarian cancer cell lines and human primary ovarian cancer cell in a dose-dependent manner. Pifithrin-μ (PFTμ, HSP70 inhibitor) decreased or removed the effects of peptide in increasing the sensitivity of ovarian cancer cells to DDP. This suggests that PGPIPN enhanced the sensitivity of ovarian cancer cells to DDP partially via reducing the activity of HSF1/HSP70 signaling pathway, thus inducing cell apoptosis and decreasing repairment of DNA damage.