Isocaloric diets with varying protein levels affected energy metabolism in young adult Sprague-Dawley rats via modifying the gut microbes: A lipid imbalance was brought on by a diet with a particularly high protein content.

Protein is the most important macro-nutrient when it comes to maximizing health, body composition, muscle growth, and recovery of body tissue. In recent years, it has been found that protein also plays an important role in metabolism and gut microbiota. This study was performed to investigate the effects of an isocaloric diet with different crude protein contents on the energy metabolism of Sprague-Dawley (SD) rats. Results revealed that compared with the 20% crude protein (CP; control) diet, the 38% CP diet improved serum parameters that are associated with dyslipidemia and glucose metabolic disorders in SD rats, whereas the 50% CP diet increased liver injury indicators and fatty acid synthesis-related genes and protein expression in the liver. Compared with the control diet, the 14% CP diet increased the abundance of colonic short-chain fatty acid-producing bacteria (Lachnospiraceae_NK4A136_group and Ruminiclostridium_9) and promoted colonic microbial cysteine and methionine metabolism, the 38% CP diet up-regulated colonic microbial lysine biosynthesis and degradation pathways, and the 50% CP diet down-regulated colonic mucosal cholesterol metabolism. Furthermore, the increase of multiple colonic enteropathogenic bacteria in the 50% CP group was associated with higher palmitic acid and stearic acid concentrations in the colonic microbes and lower cholesterol and arachidonic acid concentrations in the colonic mucosa. These findings revealed that the 14% CP and 38% CP diets improved rats' energy metabolism, while the 50% CP diet was accompanied by lipid metabolism imbalances and an increase in the abundance of multiple enteropathogenic bacteria.

Potential therapeutic effects of milk-derived exosomes on intestinal diseases.

Exosomes are extracellular vesicles with the diameter of 30 ~ 150 nm, and are widely involved in intercellular communication, disease diagnosis and drug delivery carriers for targeted disease therapy. Therapeutic application of exosomes as drug carriers is limited due to the lack of sources and methods for obtaining adequate exosomes. Milk contains abundant exosomes, several studies have shown that milk-derived exosomes play crucial roles in preventing and treating intestinal diseases. In this review, we summarized the biogenesis, secretion and structure, current novel methods used for the extraction and identification of exosomes, as well as discussed the role of milk-derived exosomes in treating intestinal diseases, such as inflammatory bowel disease, necrotizing enterocolitis, colorectal cancer, and intestinal ischemia and reperfusion injury by regulating intestinal immune homeostasis, restoring gut microbiota composition and improving intestinal structure and integrity, alleviating conditions such as oxidative stress, cell apoptosis and inflammation, and reducing mitochondrial reactive oxygen species (ROS) and lysosome accumulation in both humans and animals. In addition, we discussed future prospects for the standardization of milk exosome production platform to obtain higher concentration and purity, and complete exosomes derived from milk. Several in vivo clinical studies are needed to establish milk-derived exosomes as an effective and efficient drug delivery system, and promote its application in the treatment of various diseases in both humans and animals.

Polyphenol-rich diet mediates interplay between macrophage-neutrophil and gut microbiota to alleviate intestinal inflammation.

Dietary phenolic acids alleviate intestinal inflammation through altering gut microbiota composition and regulating macrophage activation. However, it is unclear how individual phenolic acids affect the interactions between intestinal microbiota and macrophages in the context of inflammatory bowel disease (IBD). Here, we aim to elucidate the mechanism by which phenolic acids alleviate gut inflammation. Mice with or without depletion of macrophages were administered with four individual phenolic acids including chlorogenic, ferulic, caffeic, and ellagic acids, following dextran sulfate sodium (DSS) treatment. Gut microbiota depletion and fecal microbiota transplantation were further performed in mice to investigate the role of the gut microbiota in phenolic acid-mediated protective effect. Colitis severity was evaluated using histological, serological, and immunological measurements. Absence of intestinal microbiota and macrophage deteriorate the epithelial injury in DSS colitis. Chlorogenic acid mitigated colitis by reducing M1 macrophage polarization through suppression of pyruvate kinase M 2 (Pkm2)-dependent glycolysis and inhibition of NOD-like receptor protein 3 (Nlrp3) activation. However, ferulic acid-mediated reduction of colitis was neutrophil-dependent through diminishing the formation of neutrophil extracellular traps. On the other hand, the beneficial effects of caffeic acid and ellagic acid were dependent upon the gut microbiota. In fact, urolithin A (UroA), a metabolite transformed from ellagic acid by the gut microbiota, was found to alleviate colitis and enhance gut barrier function in an IL22-dependent manner. Overall, our findings demonstrated that the mechanisms by which phenolic acid protected against colitis were resulted from the interaction between gut microbiota and macrophage-neutrophil.

L-arabinose Attenuates LPS-Induced Intestinal Inflammation and Injury through Reduced M1 Macrophage Polarization.

BACKGROUND: L-arabinose has anti-inflammatory and metabolism-promoting properties, and macrophages participate in the alleviation of inflammation; however, the mechanism by which they contribute to the anti-inflammatory effects of L-arabinose is unknown. OBJECTIVES: To investigate the involvement of macrophages in the mitigation of L-arabinose in an intestinal inflammation model induced by lipopolysaccharide (LPS). METHODS: Five-week-old male C57BL/6 mice were divided into 3 groups: a control and an LPS group that both received normal water supplementation, and an L-arabinose (ARA+LPS) group that received 5% L-arabinose supplementation. Mice in the LPS and ARA+LPS groups were intraperitoneally injected with LPS (10 mg/kg body weight), whereas the control group was intraperitoneally injected with the same volume of saline. Intestinal morphology, cytokines, tight junction proteins, macrophage phenotypes, and microbial communities were profiled at 6 h postinjection. RESULTS: L-arabinose alleviated LPS-induced damage to intestinal morphology. L-arabinose down-regulated serum tumor necrosis factor-α (TNF-α), interleukin (IL)-1ß, and IL-6, and messenger RNA (mRNA) levels of TNF-α, IL-1ß, interferon-γ (IFN-γ), and toll-like receptor-4 in jejunum and colon compared with those of the LPS group (P < 0.05). The mRNA and protein levels of occludin and claudin-1 were significantly increased by L-arabinose (P < 0.05). Interferon regulatory factor-5 (IRF-5) and signal transducer and activator of transcription-1 (STAT-1), key genes characterized by M1 macrophages, were elevated in the jejunum and colon of LPS mice (P < 0.05) but decreased in the ARA+LPS mice (P < 0.05). In vitro, L-arabinose decreased the proportion of M1 macrophages and inhibited mRNA levels of TNF-α, IL-1ß, IL-6, IFN-γ, as well as IRF-5 and STAT-1 (P < 0.01). Moreover, L-arabinose restored the abundance of norank_f__Muribaculaceae, Faecalibaculum, Dubosiella, Prevotellaceae_UCG-001, and Paraasutterella compared with those of LPS (P < 0.05) and increased the concentration of short-chain fatty acids (P < 0.05). CONCLUSION: The anti-inflammatory effects of L-arabinose are achieved by reducing M1 macrophage polarization, suggesting that L-arabinose could be a candidate functional food or nutritional strategy for intestinal inflammation and injury.

Effects of Different Combinations of Sodium Butyrate, Medium-Chain Fatty Acids and Omega-3 Polyunsaturated Fatty Acids on the Reproductive Performance of Sows and Biochemical Parameters, Oxidative Status and Intestinal Health of Their Offspring.

The aim of the study was to investigate the comparative effects of different combinations of sodium butyrate (SB), medium-chain fatty acids (MCFAs), and omega-3 polyunsaturated fatty acids (n-3 PUFAs) on the reproductive performances of sows, as well as on the biochemical parameters, oxidative statuses, and intestinal health of the sucking piglets. A total of 30 sows were randomly allocated to five treatments: (1) control diet (CON); (2) CON with 1 g/kg of coated SB and 7.75 g/kg of coated MCFAs (SM); (3) CON with 1 g/kg of coated SB and 68.2 g/kg of coated n-3 PUFAs (SP); (4) CON with 7.75 g/kg of coated MCFAs and 68.2 g/kg of coated n-3 PUFAs (MP); (5) CON with 1 g/kg of coated SB, 7.75 g/kg of coated MCFAs and 68.2 g/kg of coated n-3 PUFA (SMP). The results showed that sows fed the SP, MP, and SMP diets had shorter weaning-to-estrus intervals than those fed the CON diet (p < 0.01). The piglets in the SM, SP, and MP groups showed higher increases in the plasma catalase and glutathione peroxidase activities than those of the CON group (p < 0.01). The diarrhea incidence of piglets in the SM, SP and SMP groups was lower than that of piglets in the CON group (p < 0.01). Additionally, the addition of SM, SP, MP, and SMP to the sow diets increased the contents of immunoglobulin A, immunoglobulin G, fat, and proteins in the colostrum (p < 0.01), as well as the plasma total superoxide dismutase activities (p < 0.01) in the suckling piglets, whereas it decreased the mRNA expressions of tumor necrosis factor-α, interleukin-1ß, and toll-like receptor 4 in the jejunum mucosa of the piglets. The relative abundances of Prevotella, Coprococcus, and Blautia in the colonic digesta of the piglets were increased in the SM group (p < 0.05), and the relative abundances of Faecalibacterium increased in the SMP group (p < 0.05), compared with the CON group. The relative abundances of Collinsella, Blautia, and Bulleidia in the MP group were higher than those in the CON group (p < 0.05). Collectively, dietary combinations of fatty acids with different chain lengths have positive effects on the growth performances and intestinal health of suckling piglets.

Small extracellular vesicles from Ptpn1-deficient macrophages alleviate intestinal inflammation by reprogramming macrophage polarization via lactadherin enrichment.

Tyrosine-protein phosphatase non-receptor type 1 (Ptpn1) is known to be involved in macrophage polarization. However, whether and how Ptpn1 regulates macrophage phenotype to affect intestinal epithelial barrier function remains largely unexplored. Herein, we investigated the impact of Ptpn1 and macrophage-derived small extracellular vesicles (sEVs) on macrophage-intestinal epithelial cell (IEC) interactions in the context of intestinal inflammation. We found that Ptpn1 knockdown shifts macrophages toward the anti-inflammatory M2 phenotype, thereby promoting intestinal barrier integrity and suppressing inflammatory response in the macrophage-IEC co-culture model. We further revealed that conditioned medium or sEVs isolated from Ptp1b knockdown macrophages are the primary factor driving the beneficial outcomes. Consistently, administration of the sEVs from Ptpn1-knockdown macrophages reduced disease severity and ameliorated intestinal inflammation in LPS-challenged mice. Furthermore, depletion of macrophages in mice abrogated the protective effect of Ptpn1-knockdown macrophage sEVs against Salmonella Typhimurium infection. Importantly, we found lactadherin to be highly enriched in the sEVs of Ptpn1-knockdown macrophages. Administration of recombinant lactadherin alleviated intestinal inflammation and barrier dysfunction by inducing macrophage M2 polarization. Interestingly, sEVs lactadherin was also internalized by macrophages and IECs, leading to macrophage M2 polarization and enhanced intestinal barrier integrity. Mechanistically, the anti-inflammatory and barrier-enhancing effect of lactadherin was achieved by reducing TNF-α and NF-κB activation. Thus, we demonstrated that sEVs from Ptpn1-knockdown macrophages mediate the communication between IECs and macrophages through enrichment of lactadherin. The outcome could potentially lead to the development of novel therapies for intestinal inflammatory disorders.

Bifidobacterium animalis Promotes the Growth of Weaning Piglets by Improving Intestinal Development, Enhancing Antioxidant Capacity, and Modulating Gut Microbiota.

Probiotics are widely used to promote performance and improve gut health in weaning piglets. Therefore, the objective of this study was to investigate the effects of dietary supplementation with Bifidobacterium animalis subsp. lactis (B. animalis) JYBR-190 on the growth performance, intestine health, and gut microbiota of weaning piglets. The results showed that the dietary addition of B. animalis significantly improved growth performance and decreased diarrhea incidence. B. animalis increased villus height in the duodenum and elevated goblet cell numbers and amylase activity in the jejunum. Additionally, B. animalis supplementation markedly increased total antioxidant capacity in jejunal mucosa but declined the malondialdehyde content. B. animalis treatment did not affect the mRNA expressions associated with the intestinal barrier and inflammatory cytokine in various intestinal segments. Microbiota analysis indicated that a diet supplemented with B. animalis significantly increased the relative abundances of health-promoting bacteria in the lumen, such as Streptococcus, Erysipelotrichaceae, Coprococcus, and Oscillibacter. There was a trend for B. animalis fed piglets to have a higher relative abundance of B. animalis in ileal digesta. Moreover, B. animalis-treated pigs decreased the abundance of Helicobacter and Escherichia-Shigella in ileal mucosa-associated microbiota. In summary, this study showed that B. animalis supplementation stimulated growth performance, improved gut development, enriched beneficial bacteria abundances, and declined intestinal pathogens populations, while B. animalis had limited effects on the intestinal barrier and immune function. IMPORTANCE In the modern swine industry, weaning is a critical period in the pig's life cycle. Sudden dietary, social, and environmental changes can easily lead to gut microbiota dysbiosis, diarrhea, and a decrease in growth performance. To stabilize intestinal microbiota and promote animal growth, antibiotics were widely applied in swine diets during the past few decades. However, the side effects of antibiotics posed a great threat to public health and food safety. Therefore, it is urgent to find and develop antibiotic alternatives. The growing evidence suggested that probiotics can be preferable alternatives to antibiotics because they can modulate microbiota composition and resist pathogens colonization. In this study, our results indicated that dietary supplementation with Bifidobacterium animalis promoted growth in weaning piglets by improving gut development, increasing beneficial bacteria abundances, and declining pathogens populations.

The High Level of Xylooligosaccharides Improves Growth Performance in Weaned Piglets by Increasing Antioxidant Activity, Enhancing Immune Function, and Modulating Gut Microbiota.

The aim of this study was to investigate the effects of the high level of xylooligosaccharides (XOS) on growth performance, antioxidant capability, immune function, and fecal microbiota in weaning piglets. The results showed that 28 d body weight exhibited linear and quadratic increases (P < 0.05) with increasing dietary XOS level, as well as average daily feed intake (ADFI) on d 15-28, average daily gain (ADG) on d 15-28 and 1-28. There was a linear decrease (P < 0.05) between XOS levels and feed conversion rate (FCR) on d 1-14 and 1-28. Additionally, glutathione peroxidase (GSH-Px) showed a linear increase (P < 0.05), while the malondialdehyde (MDA) level decreased linearly and quadratically (P < 0.05) with the increasing dietary level of XOS. Moreover, the XOS treatments markedly increased the levels of immunoglobulin A (Ig A) (linear, P < 0.05; quadratic, P < 0.05), IgM (quadratic, P < 0.05), IgG (linear, P < 0.05), and anti-inflammatory cytokine interleukin-10 (IL-10) (quadratic, P < 0.05) in serum, while the IL-1ß (linear, P < 0.05; quadratic, P < 0.05) and IL-6 (linear, P < 0.05) decreased with increasing level of XOS. Microbiota analysis showed that dietary supplementation with 1.5% XOS decreased (P < 0.05) the α-diversity and enriched (P < 0.05) beneficial bacteria including Lactobacillus, Bifidobacterium, and Fusicatenibacter at the genus level, compared with the control group. Importantly, linearly increasing responses (P < 0.05) to fecal acetate, propionate, butyrate, and total short-chain fatty acids (SCFAs) were observed with increasing level of XOS. Spearman correlation analyses found that Lactobacillus abundance was positively correlated with ADG, acetate, propionate, and IgA (P < 0.05), but negatively correlated with IL-1ß (P < 0.05). Bifidobacterium abundance was positively related with ADFI, total SCFAs, IgG, and IL-10 (P < 0.05), as well as g_Fusicatenibacter abundance with ADFI, total SCFAs, and IL-10. However, Bifidobacterium and Fusicatenibacter abundances were negatively associated with MDA levels (P < 0.05). In summary, dietary supplementation with XOS can improve the growth performance in weaning piglets by increasing antioxidant capability, enhancing immune function, and promoting beneficial bacteria counts.

Gut microbiota from green tea polyphenol-dosed mice improves intestinal epithelial homeostasis and ameliorates experimental colitis.

BACKGROUND: Alteration of the gut microbiota may contribute to the development of inflammatory bowel disease (IBD). Epigallocatechin-3-gallate (EGCG), a major bioactive constituent of green tea, is known to be beneficial in IBD alleviation. However, it is unclear whether the gut microbiota exerts an effect when EGCG attenuates IBD. RESULTS: We first explored the effect of oral or rectal EGCG delivery on the DSS-induced murine colitis. Our results revealed that anti-inflammatory effect and colonic barrier integrity were enhanced by oral, but not rectal, EGCG. We observed a distinct EGCG-mediated alteration in the gut microbiome by increasing Akkermansia abundance and butyrate production. Next, we demonstrated that the EGCG pre-supplementation induced similar beneficial outcomes to oral EGCG administration. Prophylactic EGCG attenuated colitis and significantly enriched short-chain fatty acids (SCFAs)-producing bacteria such as Akkermansia and SCFAs production in DSS-induced mice. To validate these discoveries, we performed fecal microbiota transplantation (FMT) and sterile fecal filtrate (SFF) to inoculate DSS-treated mice. Microbiota from EGCG-dosed mice alleviated the colitis over microbiota from control mice and SFF shown by superiorly anti-inflammatory effect and colonic barrier integrity, and also enriched bacteria such as Akkermansia and SCFAs. Collectively, the attenuation of colitis by oral EGCG suggests an intimate involvement of SCFAs-producing bacteria Akkermansia, and SCFAs, which was further demonstrated by prophylaxis and FMT. CONCLUSIONS: This study provides the first data indicating that oral EGCG ameliorated the colonic inflammation in a gut microbiota-dependent manner. Our findings provide novel insights into EGCG-mediated remission of IBD and EGCG as a potential modulator for gut microbiota to prevent and treat IBD. Video Abstract.

Resistant Maltodextrin Alleviates Dextran Sulfate Sodium-Induced Intestinal Inflammatory Injury by Increasing Butyric Acid to Inhibit Proinflammatory Cytokine Levels.

Inflammatory bowel disease (IBD), one kind of intestinal chronic inflammatory disease, is characterized by colonic epithelial barrier injury, overproduction of proinflammatory cytokines, and fewer short-chain fatty acids (SCFAs). The present study is aimed at testing the hypothesis that resistant maltodextrin (RM), a soluble dietary fiber produced by starch debranching, alleviated dextran sulfate sodium- (DSS-) induced colitis in mice. Female C57BL/6 mice with or without oral administration of 50 mg/kg RM for 19 days were challenged with 3% DSS in drinking water to induce colitis (from day 14 to day 19). Although RM could not reverse DSS-induced weight loss or colon shortening, it reduced inflammatory cell infiltration and epithelial damage in colon tissue, as well as the transfer of intestinal permeability indicators including serum diamine oxidase (DAO) and D-lactic acid (D-LA). ELISA analysis indicated that RM significantly suppressed the increase of Th1 cytokines induced by DSS in the colon such as tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ). The levels of proinflammatory cytokines interleukin-1ß (IL-1ß), IL-17, and IL-8 in the DSS group were significantly higher than those in the control group and RM group, but no significant difference was observed in the RM-DSS group compared with the RM group. Interestingly, IL-10 levels of the DSS group were significantly higher than those of the other groups. With respect to SCFAs, DSS administration significantly decreased the concentration of faecal butyric acid while the RM-DSS group showed a tendency to increase (P = 0.08). In general, RM alleviated dextran sulfate sodium-induced intestinal inflammation through increasing the level of butyric acid and subsequently inhibiting the expression of proinflammatory cytokines.

SIRT3 deficiency is resistant to autophagy-dependent ferroptosis by inhibiting the AMPK/mTOR pathway and promoting GPX4 levels.

Ferroptosis, an autophagy-dependent cell death, is characterized by lipid peroxidation and iron accumulation, closely associated with pathogenesis of gestational diabetes mellitus (GDM). Sirtuin 3 (SIRT3) has positive regulation on phosphorylation of activated protein kinase (AMPK), related to maintenance of cellular redox homeostasis. However, whether SIRT3 can confer autophagy by activating the AMPK-mTOR pathway and consequently promote induction of ferroptosis is unknown. We used human trophoblastic cell line HTR8/SVneo and porcine trophoblastic cell line pTr2 to deterimine the mechanism of SIRT3 on autophagy and ferroptosis. The expression of SIRT3 protein was significantly elevated in trophoblastic cells exposed to high concentrations of glucose and ferroptosis-inducing compounds. Increased SIRT3 expression contributed to classical ferroptotic events and autophagy activation, whereas SIRT3 silencing led to resistance against both ferroptosis and autophagy. In addition, autophagy inhibition impaired SIRT3-enhanced ferroptosis. On the contrary, autophagy induction had a synergistic effect with SIRT3. Based on mechanistic investigations, SIRT3 depletion inhibited activation of the AMPK-mTOR pathway and enhanced glutathione peroxidase 4 (GPX4) level, thereby suppressing autophagy and ferroptosis. Furthermore, depletion of AMPK blocked induction of ferroptosis in trophoblasts. We concluded that upregulated SIRT3-enhanced autophagy activation by promoting AMPK-mTOR pathway and decreasing GPX4 level to induce ferroptosis in trophoblastic cells. SIRT3 deficiency was resistant to high glucose- and erastin-induced autophagy-dependent ferroptosis and is, therefore, a potential therapeutic approach for treating GDM.