Ferrous Bisglycinate Supplementation Modulates Intestinal Antioxidant Capacity via the AMPK/FOXO Pathway and Reconstitutes Gut Microbiota and Bile Acid Profiles in Pigs

Ferrous-sucrose complex supplementation regulates maternal plasma metabolism and the fecal microbiota composition and improves neonatal immunity and placental glucose transportation by activating the EGF/PI3K/AKT signaling pathways in sows

Pregnancy is a dynamic state involving rapid physiological changes in metabolism, affecting the health and development of the offspring. During pregnancy, the placenta constitutes a physical and immunological barrier to provide fetal nutrition through the maternal blood and prevent the exposure of the fetus to dangerous signals. Metabolic changes in the plasma, the fecal microbiota profile, and functional regulation in the placenta were studied in sows supplied with a ferrous-sucrose complex (FeSuc) from late gestation to parturition. The results revealed that maternal FeSuc supplementation enhanced arginine and proline metabolism, glutathione metabolism, with increased glutamic acid, beta-D-glucosamine, L-proline, 1-butylamine, and succinic acid and reduced sphingosine and chenodeoxycholic acid sulfate levels in the plasma. Moreover, significantly increased abundances of Christensenellaceae_R-7_group, Prevotellaceae_NK3B31_group, and Lachnospiraceae_NK4B4_group were detected in the feces of sows from the FeSuc group (P < 0.05). Spearman's correlation analysis indicated that Prevotellaceae_NK3B31_group abundances were positively correlated with glutamic acid, indoxyl sulfate, acetyl-DL-leucine, and beta-D-glucosamine, while Christensenellaceae_R-7_group was positively correlated with beta-D-glucosamine. Furthermore, maternal FeSuc supplementation significantly increased neonatal glucose (P < 0.01) and iron (P < 0.01) in the neonatal serum, significantly increased IL-10 and TGF-β1 levels in the neonatal liver (P < 0.01) and jejunum (P < 0.05), promoted the transcription of immune molecules in the placenta, and significantly increased the protein expressions of EGF (P < 0.05), PI3K (P < 0.01), p-PI3K (P < 0.001), p-AKT (P < 0.01), and glucose transporter 1 (GLUT1) (P < 0.001) in the placenta. The current study demonstrated that FeSuc supplementation regulated maternal metabolism processes by altering the fecal microbial composition and improved neonatal immunity and placental glucose transportation by activating the EGF/PI3K/AKT signaling pathways in sows.

Effects of Spinach Extract and Licorice Extract on Growth Performance, Antioxidant Capacity, and Gut Microbiota in Weaned Piglets

Anemia and weaning stress are important factors affecting piglet growth performance. Spinach extract and licorice extract have been used to improve anemia and antioxidant capacity, respectively. However, whether they have synergistic effects has not been reported. To evaluate the effects of mixed spinach extract and licorice extract on growth performance, serum biochemistry, antioxidant capacity, and gut microbiota in weaned piglets, a total of 160 weaned piglets were randomly allotted to four treatments with four replications of 10 piglets each. The four treatments were as follows: control (CON) group (basal diet), spinach extract (SE) group (basal diet + 1.5 kg/t spinach extract), licorice extract (LE) group (basal diet + 400 g/t licorice extract), and spinach extract and licorice extract (MIX) group (basal diet + 1.5 kg/t spinach extract + 400 g/t licorice extract). The results showed that, compared with the CON group, diets supplemented with spinach extract and licorice extract significantly increased the average daily gain (p < 0.05), while considerably reducing the feed-to-gain ratio (p < 0.05). Moreover, the MIX group exhibited a significant up-regulation of serum total protein, globulin, albumin, glucose, and triglyceride levels in comparison to the CON group (p < 0.05). Meanwhile, both the anemia and antioxidant capacity of piglets were effectively improved. Notably, the MIX group achieved even better results than the individual supplementation in terms of enhancing growth performance, which could potentially be attributed to the increased abundance of the Rikenellaceae_RC9_gut_group. These results demonstrated that the supplementation of diets with spinach extract and licorice extract improves the absorption of nutrients from the diet and antioxidant capacity in weaned piglets.

Effect of replacing inorganic iron with iron-rich microbial preparations on growth performance, serum parameters and iron metabolism of weaned piglets

This study aimed to investigate the effects of replacing of dietary inorganic iron with iron-rich Lactobacillus plantarum and iron-rich Candida utilis on the growth performance, serum parameters, immune function and iron metabolism of weaned piglets. Fifty-four 28-day-old healthy Duroc × Landrace × Yorkshire castrated male weanling piglets of similar body weight were randomly and equally divided into three groups. The piglets were kept in three pens per group, with six pigs in each pen. The dietary treatments were (1) a basal diet + ferrous sulfate preparation containing 120 mg/kg iron (CON); (2) a basal diet + iron-rich Candida utilis preparation containing 120 mg/kg iron (CUI); and (3) a basal diet + iron-rich Lactobacillus plantarum preparation containing 120 mg/kg iron (LPI). The entire feeding trial lasted for 28 days, after which blood, viscera, and intestinal mucosa were collected. The results showed no significant difference in growth parameters and organ indices of the heart, liver, spleen, lung, and kidney of weaned piglets when treated with CUI and LPI compared with the CON group (P > 0.05). However, CUI and LPI significantly reduced the serum contents of AST, ALP, and LDH (P < 0.05). Serum ALT content was significantly lower in the LPI treatment compared to the CON group (P < 0.05). Compared to CON, CUI significantly increased the contents of serum IgG and IL-4 (P < 0.05), and CUI significantly decreased the content of IL-2. LPI significantly increased the contents of serum IgA, IgG, IgM and IL-4 (P < 0.05), while LPI significant decreased the levels of IL-1β, IL-2, IL-6, IL-8, and TNF-α compared to CON (P < 0.05). CUI led to a significant increase in ceruloplasmin activity and TIBC (P < 0.05). LPI significantly increased the contents of serum Fe and ferritin, and increased the serum ceruloplasmin activity and TIBC compared to CON (P < 0.05). Furthermore, CUI resulted in a significant increase in the relative mRNA expression of FPN1 and DMT1 in the jejunal mucosa (P < 0.05). LPI significantly increased the relative mRNA expression of TF, FPN1, and DMT1 in the jejunal mucosa (P < 0.05). Based on these results, the replacement of dietary inorganic iron with an iron-rich microbial supplement could improve immune function, iron absorption and storage in piglets.

A High-Fat, High-Cholesterol Diet Promotes Intestinal Inflammation by Exacerbating Gut Microbiome Dysbiosis and Bile Acid Disorders in Cholecystectomy

Patients with post-cholecystectomy (PC) often experience adverse gastrointestinal conditions, such as PC syndrome, colorectal cancer (CRC), and non-alcoholic fatty liver disease (NAFLD), that accumulate over time. An epidemiological survey further revealed that the risk of cholecystectomy is associated with high-fat and high-cholesterol (HFHC) dietary intake. Mounting evidence suggests that cholecystectomy is associated with disrupted gut microbial homeostasis and dysregulated bile acids (BAs) metabolism. However, the effect of an HFHC diet on gastrointestinal complications after cholecystectomy has not been elucidated. Here, we aimed to investigate the effect of an HFHC diet after cholecystectomy on the gut microbiota-BA metabolic axis and elucidate the association between this alteration and the development of intestinal inflammation. In this study, a mice cholecystectomy model was established, and the levels of IL-Iβ, TNF-α, and IL-6 in the colon were increased in mice fed an HFHC diet for 6 weeks. Analysis of fecal BA metabolism showed that an HFHC diet after cholecystectomy altered the rhythm of the BA metabolism by upregulating liver CPY7A1, CYP8B1, and BSEP and ileal ASBT mRNA expression levels, resulting in increased fecal BA levels. In addition, feeding an HFHC diet after cholecystectomy caused a significant dysbiosis of the gut microbiota, which was characterized by the enrichment of the metabolic microbiota involved in BAs; the abundance of pro-inflammatory gut microbiota and related pro-inflammatory metabolite levels was also significantly higher. In contrast, the abundance of major short-chain fatty acid (SCFA)-producing bacteria significantly decreased. Overall, our study suggests that an HFHC diet after cholecystectomy promotes intestinal inflammation by exacerbating the gut microbiome and BA metabolism dysbiosis in cholecystectomy. Our study also provides useful insights into the maintenance of intestinal health after cholecystectomy through dietary or probiotic intervention strategies.

Dietary iron regulates intestinal goblet cell function and alleviates Salmonella typhimurium invasion in mice

Iron is an important micronutrient that plays a vital role in host defenses and bacterial pathogenicity. As iron treatments increase the risk of infection by stimulating the growth and virulence of bacterial pathogens, their roles in anti-infection immunity have frequently been underestimated. To estimate whether adequate dietary iron intake would help defend against pathogenic bacterial infection, mice were fed iron-deficient (2 mg kg-1 feed), iron-sufficient (35 mg kg-1 feed), or iron-enriched diet (350 mg kg-1 feed) for 12 weeks, followed by oral infection with Salmonella typhimurium. Our results revealed that dietary iron intake improved mucus layer function and decelerated the invasion of the pathogenic bacteria, Salmonella typhimurium. Positive correlations between serum iron and the number of goblet cells and mucin2 were found in response to total iron intake in mice. Unabsorbed iron in the intestinal tract affected the gut microbiota composition, and the abundance of Bacteroidales, family Muribaculaceae, was positively correlated with their mucin2 expression. However, the results from antibiotic-treated mice showed that the dietary iron-regulated mucin layer function was not microbial-dependent. Furthermore, in vitro studies revealed that ferric citrate directly induced mucin2 expression and promoted the proliferation of goblet cells in both ileal and colonic organoids. Thus, dietary iron intake improves serum iron levels, regulates goblet cell regeneration and mucin layer function, and plays a positive role in the prevention of pathogenic bacteria.

The gut microbiota-bile acid axis mediates the beneficial associations between plasma vitamin D and metabolic syndrome in Chinese adults: A prospective study

BACKGROUND & AIMS

Previous studies have suggested that circulating 25-hydroxyvitamin D (25 [OH]D, VD) and the gut microbiota-bile acid axis play crucial roles in metabolic health. Exploring the mediating role of the gut microbiota-bile acid axis would improve our understanding of the mechanisms underlying the effects of VD on human metabolic health. This study examined the association between plasma 25(OH)D and the prevalence/incidence of metabolic syndrome (MetS) and the mediating role of the gut microbiota-bile acid axis.

METHODS

This prospective study included 3180 participants with plasma 25(OH)D data at baseline and 2966 participants with a 9-year follow-up. MetS was determined every three years. The gut microbiota was analyzed by 16S rRNA sequencing in 1752 participants, and targeted bile acid metabolites in feces were further determined in 974 participants using UPLC‒MS/MS at the middle of the study. Mediating roles of microbiota and bile acids in the VD-MetS associations were analyzed using mediation/path analyses adjusted for potential confounders.

RESULTS

Among the 2966 participants who were followed-up, 1520, 193, 647, and 606 were MetS-free (normal), recovered, had incident MetS, and had persistent MetS, respectively. The multivariable-adjusted ORs (95% CIs) of MetS prevalence were 0.65 (0.50, 0.84) for baseline MetS and 0.46 (0.33, 0.65) for 9-year persistent MetS in quartile 4 (compared to quartile 1) of plasma 25(OH)D (median: 37.7 vs. 19.6, ng/ml). The corresponding HR (95% CI) of 9-year MetS incidence was 0.71 (0.56, 0.90) (all P-trend < 0.05). Higher VD concentrations were associated with greater α-diversity of the gut microbiota, which was inversely correlated with MetS risk. The groups classified by VD and MetS status had significantly different β-diversity. Ruminiclostridium-6 and Christensenellaceae R-7 group were enriched in the high-VD group and were inversely associated with MetS. However, opposite associations were observed for Lachnoclostridium and Acidaminococcus. The overlapping differential microbial score (ODMS) developed from the four differential genera explained 12.2% of the VD-MetS associations (P_mediation = 0.015). Furthermore, the fecal bile acid score created from 11 differential bile acids related to ODMS and MetS mediated 34.2% of the association between ODMS and MetS (P_mediation = 0.029). Path analyses showed that the inverse association between plasma 25(OH)D and MetS could be mediated by the gut microbiota-bile acid axis.

CONCLUSIONS

The findings suggest that the gut microbiota-bile acid axis partially mediates the beneficial association between plasma 25(OH)D and the risk of persistent MetS and incident MetS in the Chinese population.