Gly-Pro-Ala peptide and FGSHF3 exert protective effects in DON-induced toxicity and intestinal damage via decreasing oxidative stress.

Deoxynivalenol (DON), a common mycotoxin, usually induces oxidative stress and intestinal injury of humans and animals. This study aims to investigate the protective effect of Gly-Pro-Ala (GPA) peptide, isolated from fish skin gelatin hydrolysate fraction 3 (FGSHF3), on alleviating the toxicity and oxidative stress induced by DON in the mice and IPEC-J2 cells. DON treatment decreases average daily gain and feeds intake, which causes enlargement of the liver and spleen. FGSHF3 (200 mg/kg) and GPA (200 mg/kg) treatment significantly increase average daily gain and inhibits enlargement of the liver and spleen. Furthermore, FGSHF3 and GPA treatment significantly alleviates intestinal injury and maintains tight junction in mice and IPEC-J2 cells. FGSHF3 and GPA treatment significantly inhibits ROS and MDA production and enhances antioxidant enzyme activity, such as CAT, SOD-1, GCLM, GCLC, and GSH-PX. Furthermore, FGSHF3 and GPA treatment promote Nrf2 migration from the cytoplasm to the nucleus, resulting in exerting antioxidant effects. And its effects are abolished after Nrf2 is knockdown by siRNA. Overall, our results suggest GPA peptide may be a promising candidate for the alleviation of DON-induced toxicity in humans and animals.

Fish Skin Gelatin Hydrolysate Production by Ginger Powder Induces Glutathione Synthesis To Prevent Hydrogen Peroxide Induced Intestinal Oxidative Stress via the Pept1-p62-Nrf2 Cascade.

Gelatin hydrolysate was reported to contain large amounts of biologically active peptides with excellent antioxidant properties. However, its inducement of antioxidant response within cells and the underlying molecular mechanism are far from clear. Here, gelatin from Nile tilapia skin was hydrolyzed by ginger protease to produce antioxidant hydrolysate, and three fish skin gelatin hydrolysate fractions (FSGHFs) were obtained by ultrafiltration. Fractionation of the hydrolysate increased the free radical scavenging capacity of the FSGHFs, particularly FSGHF3, which showed the lowest molecular weight (below 1000 Da). Furthermore, FSGHF3 treatment prior to H2O2 exposure increased cell viability and membrane integrity in IPEC-J2 cells. H2O2-induced ROS production and epithelial barrier damage were suppressed by FSGHF3 pretreatment. FSGHF3 stimulated the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2), along with increases in the mRNA and protein expression of catalytic and modulatory subunits of γ-glutamylcysteine ligase as well as in the level of glutathione. Silencing of Nrf2 or p62 (an upstream regulator of Nrf2) suppressed FSGHF3-induced Nrf2 activation and its protection against H2O2-induced oxidative stress. Moreover, oligopeptides in FSGHF3 may mediate the cytoprotective effect against oxidative stress, which was confirmed by the result that FSGHF3 failed to inhibit the ROS production in H2O2-exposed cells with the knockdown of Pept1 (an oligopeptide transporter). Therefore, FSGHF3 can induce glutathione synthesis and prevent oxidative stress through the Pept1-p62-Nrf2 cascade and thus may be a functional food for gastrointestinal dysfunction.

Metabolic Syndrome During Perinatal Period in Sows and the Link With Gut Microbiota and Metabolites.

In humans, the metabolic and immune changes occurring during perinatal period also describe metabolic syndrome. Gut microbiota can cause symptoms of metabolic syndrome in pregnant women. Increased gut permeability is also involved in metabolic disorders in non-pregnant hosts. However, longitudinal studies investigating the changes in metabolic characteristics, gut microbiota, and gut permeability of sows throughout pregnancy and lactation are lacking. The correlation between gut microbiota and metabolic status of sows is also poorly known. The present study was conducted to investigate the temporal variations in sow metabolic characteristics, gut microbiota, gut permeability, and gut inflammation at days 30 (G30) and 109 (G109) of gestation and days 3 (L3) and 14 (L14) of lactation. Results showed that insulin sensitivity was decreased in L3. Circulating concentrations of pro-inflammatory cytokine IL-6 increased in G109 and L3. 16S rRNA gene sequencing of the V3-V4 region showed that gut microbiota changed dramatically across different reproductive stages. The bacterial abundance and alpha diversity in L3 were the lowest. The phyla Proteobacteria and Fusobacteria exhibited the highest relative abundance in L3. Among the genera, Bacteroides, Escherichia_Shigella, and Fusobacterium were highest, but Oscillospira the lowest, in relative abundance in L3. The fecal levels of acetate and total short-chain fatty acids were increased in G109, but fecal butyrate concentrations were markedly decreased in L3. The plasma zonulin concentrations, a biomarker for gut permeability, were increased in G109 and L3. The plasma endotoxin concentrations were increased in L3. Furthermore, levels of fecal lipocalin-2 and pro-inflammatory cytokines IL-6 and TNF-α were increased in G109 and L3. In contrast, fecal levels of anti-inflammatory cytokine IL-10 were significantly decreased in G109 and L3. Additionally, the increased relative abundances of Fusobacterium in L3 were positively correlated with plasma zonulin and fecal endotoxin but negatively correlated with fecal IL-10. These findings indicate that the mother sow exhibits a metabolic syndrome and dramatical changes in gut microbiota during perinatal period, especially in early lactation. Besides, increased gut permeability and plasma endotoxin concentrations caused by negative microbial changes would possibly be the potential mechanisms under which sow's metabolic disorders and inflammatory status were exacerbated during early lactation.